seismic provisions ofmodel nehrp recommended … · boca, 1994 and 1997 ubc, 1994 and 1997 sbc,...

ICSSC TR-20

P898-1?258811111111111111 "III"1111111111

NIST GCR 98-755

Comparison of the Seismic Provisions of ModelBuilding Codes and Standards

to the 1994 NEHRP Recommended Provisions

Degenkolb EngineersSan Francisco, California

A report to:

Building and Fire Research LaboratoryNational Institute of Standards and TechnologyGaithersburg, MD 20899

August 1998

U. S. Department of CommerceWilliam M. Daley, SecretaryTechnology AdministrationGary Bachula, Acting Under Secretary for TechnologyNational Institute of Standards and TechnologyRaymond G. Kammer, Director

REPRODUCED BY: ~U.S. Department of Commerce .-

National Technical Information ServiceSpringfield, Virginia 22161

ACKNOWLEDGEMENT

Project participants - Degenkolb Engineers:

Chris D. Poland

Jon A. Heintz

Darrick Hom

Laurie Iida

Leader - Earthquake Engineering Group (NIST):

Riley Chung

PROTECTED UNDER INTERNATIONAL COPYRIGHTALL RIGHTS RESERVED.NATIONAL TECHNICAL INFORMATION SERVICEU.S. DEPARTMENT OF COMMERCE

Reproduced Irombest available copy.

NIST Code Comparison

TABLE OF CONTENTS

1.0 EXECUTIVE SlJMMARY 1

2.0 IN"TRODUCTION 3

3.0 1994 NEHRP PROVISIONS 5

3.1 OVERVIEW OF NEHRP PROVISIONS 5

3.2 OVERVIEW OF CHANGES BETWEEN 1991 AND 1994 5

3.2.1 Chapter 1: General Provisions (Testing & Inspection) 6

3.2.2 Chapter 2: Structural Design, Criteria, Analysis, and Procedure(Seismic Loads) 6

3.2.3 Chapter 3: Architectural, Mechanical, and Electrical Components DesignRequirements 7

3.2.4 Chapter 4: Foundation Design Requirements 7

3.2.5 Chapter 5: Steel Structure Design Requirements 7

3.2.6 Chapter 6: Concrete Structure Design Requirements 7

3.2.7 Chapter 7: Composite Steel and Concrete Structure Design Requirements 8

3.2.8 Chapter 8: Masonry Structure Design Requirements 8

3.2.9 Chapter 9: Wood Structure Design Requirements 8

4.0 COl\1PARISON OF 1996 BOCA TO 1994 NEHRP 10

4.1 OVERVIEW OF BOCA PROVISIONS 10

4.2 COl\1PARISON OF BOCA TO NEHRP 11

4.2.1 Chapter 1: General Provisions (Testing & Inspection) 11









4.3 CONCLUSIONS REGARDING BOCA 13

Table of Contents -i- NIST Code Comparison

5.0 COMPARISON OF 1997 UBC TO 1994 NEHRP 14

5.1 OVERVIEW OF UBC PROVISIONS 14

5.2 COMPARISON OF UBC TO NEHRP 15

5.2.1 Chapter 1: General Provisions (and Testing & Inspection) 15









5.3 CONCLUSIONS REGARDING UBC 20

6.0 COMPARISON OF 1997 SBC TO 1994 NEHRP 21

6.1 OVERVIEW OF SBC PROVISIONS 21

6.2 COMPARISON OF SBC TO NEHRP 226.2.1 Chapter 1: General Provisions (Testing & Inspection) 22









6.3 CONCLUSIONS REGARDING SBC 24

Table of Contents - ii- NIST Code Comparison

7.0 COMPARISON OF ASCE 7-95 TO 1994 NEHRP 25

7.1 OVERVIEW OF ASCE 7 PROVISIONS 25

7.2 COMPARISON OF ASCE 7 TO NEHRP 26










7.3 CONCLUSIONS REGARDING ASCE 7 29

8.0 COMPARISON OF 1995 OTFDC TO 1994 NEHRP 30

8.1 OVERVIEW OF OTFDC PROVISIONS 30

8.2 COMPARISON OF OTFDC TO NEHRP 31






8.2.6 Chapter 6: Concrete Structure Design Requirements .33




8.3 CONCLUSIONS REGARDING OTFDC 34

9.0 CONCLUSIONS 35

REFERENCES 36

Table of Contents - iii- NIST Code Comparison

Detailed Comparison Tables

Table lA: Changed Provisions in BOCA and NEHRP Judged Not Equivalent.. 37

Table lB: Changed Provisions in BOCA and NEHRP Judged Equivalent 53

Table 2A: Changed Provisions in UBC and NEHRP Judged Not Equivalent 70

Table 2B: Changed Provisions in UBC and NEHRP Judged Equivalent 86

Table 3A: Changed Provisions in SBC and NEHRP Judged Not Equivalent 108

Table 3B: Changed Provisions in SBC and NEHRP Judged Equivalent 124

Table 4A: Changed Provisions in ASCE 7 and NEHRP Judged Not Equivalent.. .. 138

Table 4B: Changed Provisions in ASCE 7 and NEHRP Judged Equivalent 150

Table SA: Changed Provisions in OTFDC and NEHRP Judged Not Equivalent 167

Table 5B: Changed Provisions in OTFDC and NEHRP Judged Equivalent orNot Relevant 173

Table of Contents - iv- NIST Code Comparison

1.0 EXECUTIVE SUMMARY

Executive Order 12699, Seismic Safety ofFederal andFederally Assistedor RegulatedNew Building Construction, requires that all federally owned, leased, assisted, andregulated buildings be designed and constructed in accordance with appropriate seismicstandards. The Interagency Committee on Seismic Safety in Construction (ICSSC) hasrecommended the use ofbuilding codes which are substantially equivalent to theNational Earthquake Hazard Reduction Program RecommendedProvisionsfor theDevelopment ofSeismic Regulationsfor New Buildings (NEHRP Provisions).

The National Institute of Standards and Technology has commissioned a comparisonbetween the NEHRP Provisions and selected model building codes and standards. Theobjective of this study is to determine whether or not the seismic and material designprovisions of the latest model building codes and standards are substantially equivalentto, or exceed, the 1994 NEHRP Provisions. The model codes and standards underconsideration are the 1996 BOCA National Building Code (BOCA), 1997 ICBO UniformBuilding Code (UBC), 1997 SBCCI StandardBuilding Code (SBC), ASCE 7-95Minimum Design Loadsfor Buildings and Other Structures (ASCE 7), and 1995 CABOOne and Two Family Dwelling Code (OTFDC).

This report builds on the conclusions of two previous reports prepared for NationalInstitute of Standards and Technology (NIST 95674 and NIST 91598). These previouscomparison reports have concluded that previous editions ofthese model codes andstandards were substantially equivalent to NEHRP. In building on the conclusion ofpastequivalence, it is only necessary to compare and evaluate changes that have occurredbetween the previous editions and the most recent editions ofthe model codes andstandards in question. This report summarizes and documents changes in each modelcode or standard since the date of the last comparison report. It then compares thecurrent version of each document to the 1994 NEHRP Provisions and renders a judgmentregarding equivalence. It contains a discussion providing an overview ofthe comparisonresults and concludes with a series of tables providing a detailed side-by-side comparisonof changed provisions.

In the past BOCA has adopted the NEHRP Provisions directly without manymodifications. However, the 1996 BOCA did not incorporate many of the changes thatwere made to the 1994 NEHRP Provisions. Therefore, the documents were found to beequivalent in intent but not equivalent in design values. The conclusion ofthecomparison is that NEHRP will provide a higher level ofsafety than the 1996 BOCACode because of differences in design values and the documents are judged notequivalent.

Executive Summary - 1 - NIST Code Comparison

The 1997 UBC was substantially revised to utilize a strength based design approach. Theseismic design basis change in UBC allowed a more direct comparison of the twodocuments. They were found to be equivalent in intent and essentially equivalent indesign values with some exceptions. These exceptions are documented in the sections~~w '

In the past SBCCI has adopted the NEHRP Provisions directly without manymodifications. However, the 1997 SBC did not incorporate many ofthe changes thatwere made to the 1994 NEHRP Provisions. Therefore, the documents were found to beequivalent in intent but not equivalent in design values. The conclusion ofthecomparison is that NEHRP will provide a higher level of safety than the 1997 SBC Codebecause of differences in design values and the documents are judged not equivalent.

For the determination ofloads ASCE 7 has developed its own guidelines. For all otheraspects of the standard, ASCE 7 incorporates the 1994 NEHRP Provisions, with somerevisions. The documents were found to be equivalent in intent and equivalent in designvalues with some exceptions. These exceptions are documented in the sections thatfollow.

The scope of OTFDC is limited to wood frame residential construction, which representsa small fraction ofwhat is addressed in the NEHRP Provisions. Because ofthis, thecomparison has been limited to only those issues common to both OTFDC and NEHRP.Since NEHRP references OTFDC for conventional construction provisions, thedocuments are judged equivalent in that regard. For engineered construction, OTFDChas only minimal provisions on earthquake-resistant design and the documents are judgednot equivalent in that regard. The conclusion ofthe comparison is that OTFDC and 1994NEHRP Provisions are judged equivalent when conventional construction provisions areapplicable, and are judged not equivalent when an engineered design is required.

Executive Summary -2- NIST Code Comparison

2.0 INTRODUCTION

Executive Order 12699, Seismic Safety ofFederal andFederally Assisted or RegulatedNew Building Construction, requires that all federally owned, leased, assisted, andregulated buildings be designed and constructed in accordance with appropriate seismicstandards. The Interagency Committee on Seismic Safety in Construction (ICSSC) hasrecommended the use of building codes which are substantially equivalent to theNational Earthquake Hazard Reduction Program RecommendedProvisionsfor theDevelopment ofSeismic Regulationsfor New Buildings (NEHRP Provisions).

The National Institute of Standards and Technology has commissioned a comparisonbetween the NEHRP Provisions and selected model building codes and standards. Theobjective of this study is to determine whether or not the seismic and material designprovisions of the latest model building codes and standards are substantially equivalentto, or exceed, the 1994 NEHRP Provisions. The model codes and standards underconsideration are the 1996 BOCA National Building Code (BOCA), 1997 ICBO UniformBuilding Code (UBC), 1997 SBCCI Standard Building Code (SBC), ASCE 7-95Minimum Design Loadsfor Buildings and Other Structures (ASCE 7) and 1995 CABOOne and Two Family Dwelling Code (OTFDC).

This report builds on the conclusions oftwo previous reports prepared for NationalInstitute of Standards and Technology (NIST 95674 and NIST 91598). These previouscomparison reports have concluded that previous editions of these model codes andstandards were substantially equivalent to NEHRP. In building on the conclusion ofpastequivalence, it is only necessary to compare and evaluate changes that have occurredbetween the previous editions and the most recent editions ofthe model codes andstandards in question. This report summarizes and documents changes in each modelcode or standard since the date ofthe last comparison report. It then compares thecurrent version of each document to the 1994 NEHRP Provisions and renders a judgmentregarding equivalence. It contains a discussion providing an overview ofthe comparisonresults and concludes with a series of tables providing a detailed side-by-side comparisonof changed provisions.

Introduction -3- NIST Code Comparison

Two versions of the NEHRP Provisions and each model code and standard are reviewedand documented. These include the 1991 and 1994 NEHRP Provisions, 1993 and 1996BOCA, 1994 and 1997 UBC, 1994 and 1997 SBC, ASCE 7-93 and ASCE 7-95, and1992 and 1995 OTFDC. Comparisons are made on the basis of seismic provisions,material design provisions, foundation design requirements, quality assurance provisions,and non-structural element design requirements. Following a review ofthe relevantsections ofboth the previous edition and the current edition ofeach code and standard,changes between editions are documented, the impact ofthe changes are evaluated, andcomparisons are made to the 1994 NEHRP Provisions. In the comparison, the documentsare judged equivalent if the model code or standard provisions are equivalent to, or morestringent than, the requirements in NEHRP. The documents are judged not equivalent ifthe provisions in NEHRP are more stringent than the requirements in the model buildingcode or standard. In comparing the documents, only changes that were judged to besubstantive were documented.

In certain instances NEHRP includes provisions that the model codes or standards do not.When the model codes or standards do not have specific provisions regarding criteria,elements or systems, the design is left to the discretion ofthe designer. Depending on thejudgment ofthe designer, the design mayor may not be equivalent to NEHRP.Therefore, when the model code or standard is silent on certain issues, equivalence maynot be judged. In the case ofOTFDC, since the scope is limited to wood frameresidential construction, the comparison is limited to only those provisions which arepresent in both NEHRP and OTFDC. NEHRP Provisions that are beyond the scope ofOTFDC are judged not relevantto the comparison.

What follows is a general discussion ofthe 1994 NEHRP Provisions and the changes thathave been made since 1991, followed by a general discussion ofthe comparison betweenthe major changes in NEHRP and the model codes and standards. Each comparison is astand-alone section. Detailed side by side comparisons are included in tables followingthe discussion. The tables form the basis ofthe conclusions regarding equivalence, andare intended to be used when more detailed information is of interest. The tables arearranged according to NEHRP section numbers, and changed provisions judged notequivalent have been grouped together in separate tables from those judged equivalentfor. .eaSler companson.

Introduction -4- NIST Code Comparison

3.0 1994 NEHRP PROVISIONS

3.1 Overview of NEHRP Provisions

The Federal Emergency Management Agency (FEMA) has contracted the BuildingSeismic Safety Council (BSSC) to develop the National Hazards Reduction Program(NEHRP) Provisions for new buildings. One of the primary goals of the program is toreduce or mitigate losses from earthquakes. The NEHRP Recommended Provisions forSeismic Regulations for New Buildings are recommended provisions that are sometimesadopted by codes and local governments. The 1994 edition of the NEHRP Provisions isthe third update of the document. The NEHRP Provisions will be the basis for the 2000International Building Code.

The NEHRP Provisions outline a strength-based approach to design that represents thestate of knowledge in seismic design. The seismic design provisions incorporate currentresearch and knowledge from previous earthquakes. Seismicity maps are used to assessthe seismic hazard ofa particular region. Forces and seismic design requirements areincreased with increased seismic hazard. The seismic performance category (SPC) ofastructure, which is based on occupancy as well as the seismicity, determines the level ofdetailing and design requirements. The seismic performance category is used to obtainhigher levels of performance, however, it does not influence the force level. In the baseshear equation, a factor (R) which accounts for system response and ductility, reduces theground motion to a design level. The design base shear varies with l/T2f3, where T is theperiod of the structure.

3.2 Overview of Changes Between 1991 and 1994

The document is organized in code format. The organizational structure of the NEHRPProvisions was completely revised in the 1994 edition. Changes made with respect toformatting are not documented in this report. Chapters 1 through 9 and Appendix A ofthe 1994 editions, and the corresponding chapters in the 1991 edition are reviewed.Appendix A documents the differences between the 1994 and 1991 editions oftheprovisions. The side by side comparison tables provide more detailed documentation ofthe NEHRP changes. Only changes that were judged to be substantial are included in thetables. Provisions that are judged not equivalent to the model codes and standards arelocated in a separate table than provisions that are judged equivalent.

Major changes to the provisions are as follows:

NEHRP -5- NIST Code Comparison

3.2.1 Chapter 1: General Provisions (Testing & Inspection)

Soil profile types were redefined and expanded. Unlike the previous 4 soil types, the 6new types are based quantitatively on shear wave velocity. Recorded data and analyticalstudies ofground motion propagation through soil are the basis ofthe use of shear wavevelocity as an appropriate measure of soil amplification characteristics. There is no directcorrelation between the previous and new soil types, and the change in types will yielddifferent seismic coefficient values.

New seismic coefficients were introduced to replace previous coefficients. In general,the change produces more stringent loads and requirements for structures on soft soilsand less stringent loads and requirements for structures on hard rock. The change affectsall provisions that refer to the coefficients.

The special inspection requirements were modified. Some ofthe changes made therequirements more stringent and some made them less. The requirement for continuousspecial inspection for the placement ofconcrete in foundations was added. Therequirement for continuous special inspection for construction ofdrilled piles andcaissons was changed to periodic inspection. The requirement for periodic inspection ofplacement ofreinforcing steel in foundations, and during and upon completion ofreinforcing steel placement in intermediate concrete moment frames and concrete shearwalls was added. The requirement for periodic special inspection ofplacement of steel inreinforced masonry shear walls and ordinary moment frames and during placement ofconcrete in reinforced concrete frames and shear walls was deleted. The requirement forspecial inspection during and on completion ofthe placement ofconcrete for intermediateand special moment frames and boundary members of concrete shear walls, and after thecompletion of placement ofprestressing steel was added.

3.2.2 Chapter 2: Structural Design, Criteria, Analysis, and Procedure(Seismic Loads)

The base shear equation was revised to incorporate the new soil profile types and seismiccoefficients described in Chapter 1.

Composite systems were added to the list ofbuilding systems. Response values areincluded for the new composite systems.

The load combinations now reference ASCE 7-93. In earthquake load combinations, thedead load factor is slightly higher but the live and snow load factors are typically lower.The vertical earthquake loads depend on Ca where they previously depended on A,. Thenew vertical loads will be less for soil profile A, equivalent for soil type B and in mostcases larger for soil types C, D and E.

New sections were added that include provisions for seismically isolated and nonbuildingstructures. An appendix was added to introduce passive energy dissipation systems.


3.2.3 Chapter 3: Architectural, Mechanical, and Electrical Components DesignRequirements

The fonnulas to calculate the loads on architectural, mechanical and electrical systemswere incorporated into general fonnulas applicable to all equipment. The loads are nowdependent on a system amplification, ductility and importance factor. To match themeasured response in buildings in recent earthquakes, the loads that result from the newequations are generally higher.

New requirements for bracing ofnonstructural items such as access floors and suspendedceilings were added. The weight to be used in the force calculations, bracing andclearance requirements are among the new provisions that have been included in thissection.

3.2.4 Chapter 4: Foundation Design Requirements

Because of changes to seismic coefficients, the design loads for ties between individualpile caps, drilled piers, or caissons were revised. The design loads that were previously afunction ofAv are now a function of Ca. With this change, the design forces are lower forhard rock and higher for soft soils.

Individual spread footings are now required to have ties in soft soil only. Previously, tieswere required for conditions when the soil was anything other than rock.

3.2.5 Chapter 5: Steel Structure Design Requirements

Seismic Provisionsfor Structural Steel Buildings was added as a reference. Provisionsduplicating this infonnation were removed and the length of the section was reduced.

3.2.6 Chapter 6: Concrete Structure Design Requirements

Requirements for precast concrete elements and connections were added. Currently, if aprecast element emulates the behavior of monolithic reinforced concrete, it may beincluded in the seismic force resisting system. The required yielding location andstrength of the connection relative to the frame have been specified.

Additional requirements for diaphragms and coupling beams were added. The minimumrequired thickness ofa cast-in-place concrete diaphragm must now be at least 2 inchesthick. The minimum thickness of a cast-in-place reinforced topping slab bonded to aprecast diaphragm must now be at least 2-1/2 inches thick, and the connections andbonding must be in accordance with specified provisions.


A provision which states that anchors shall be detailed so that the connection failure isinitiated by the failure of the anchor steel rather than the failure ofthe surroundingconcrete was added. The formula to calculate the strength in tension governed byconcrete failure was revised and the resulting capacity is less. The interaction equationsto check the capacity for a combination oftension and shear were revised and are nowless stringent.

There are new limitations in the application ofplain concrete. For structures in seismicperformance category C, the application of plain concrete elements has new restrictions.Plain concrete is no longer permitted in buildings assigned to seismic performancecategory D or E, with some exceptions.

3.2.7 Chapter 7: Composite Steel and Concrete Structure Design Requirements

This new chapter covers the design requirements for composite systems and elements.For the most part the user is directed to references in the concrete and steel chapters,however, there are additional requirements that are specific to composite systems andelements. Ties spacing and minimum tube thickness are among the additionalrequirements that have been given.

3.2.8 Chapter 8: Masonry Structure Design Requirements

The masonry chapter was revised to strength based design. Allowable stress designprovisions were moved to the appendix and ultimate strength design provisions weremoved from the appendix into the main body ofthe provisions. Various provisions suchas the bundling ofbars, reinforcement development formulas and the formula to calculatethe shear strength of masonry were revised in this chapter.

3.2.9 Chapter 9: Wood Structure Design Requirements

Using factors, NEHRP revises allowable stress design to strength design. The factor usedto increase the allowable working stress values to ultimate strength values was increasedfrom 2.0 to 2.16. Additionally, several phi factors were reduced. In general, thecombination provides a lower nominal capacity than the previous provisions.

The criteria for the application ofconventional construction provisions was revised.Some ofthe limits are more stringent and some are less. The height ofthe building is nolonger a factor in determining the limits of conventional construction. The requiredspacing between braced walls has been increased for seismic performance categories Aand B. Previously all SPC A buildings could use conventional construction, now thereare limitations. Previously the maximum number of stories permitted for conventionalconstruction of SPC C building was 1 and now it is 2. Previously SPC D buildings couldnot utilize conventional construction in seismic hazard exposure groups IT and Ill, andnow conventional construction may be used for 1 story buildings with a maximumdistance between braced walls of25 feet.


In engineered construction, NEHRP no longer allows materials other than structural usematerials to be part ofthe seismic force resisting system. This precludes the use ofgypsum board and stucco on shear walls in all buildings other than conventionalconstruction.


4.0 COMPARISON OF 1996 BOCA TO1994 NEHRP

Previous reports concluded that the 1993 BOCA and the 1991 NEHRP Provisions weresubstantially equivalent. Since that time, changes have occurred in both documentswhich mayor may not be equivalent. This section summarizes the changes and makes acomparison between the current versions of both documents. Further documentation ofchanges and detailed side-by-side comparisons are contained in Tables lA and IB.

4.1 Overview of BOCA Provisions

The Building Officials and Code Administrators (BOCA) assembles the BOCA NationalBuilding Code and has included some form of seismic design provisions since itsinception in 1950. The stated intent ofthe code is to provide minimum standards toinsure the public safety, health and welfare. Since 1992, BOCA has incorporated theNEHRP Provisions for seismic design. Thus, the methodology ofthe code is the same asNEHRP. It uses a strength-based approach, the same seismicity maps, the same seismicperformance categories, the same R values, and the seismic forces vary with the inverseofT2I3.

The changes between the 1993 and 1996 editions ofBOCA are summarized below.Chapters 16 through 19, and 21 through 23 in the 1996 code are included in thiscomparison.

Few changes were made to formulas calculating seismic forces for structural,architectural, mechanical and electrical components. These sections have remainedessentially the same from the 1993 to the 1996 edition.

Provisions regarding soil testing, foundation walls, and retaining walls, were rewrittenand expanded such that they form individual sections rather than portions of the seismicdesign provisions.

The materials sections changed to the extent that BOCA has adopted the most currentstandards with few modifications. BOCA refers to AISC for steel, ACI for concrete andmasonry, and AFPA for wood. BOCA, however, included new restrictions on the use ofparticleboard in subflooring and roof sheathing in the wood section.

Comparisons between the substantial changes in each document are summarized in thefollowing section. The comparisons are arranged according to 1994 NEHRP chapters.For a more detailed and inclusive comparison, see Tables lA and IB.

BOCA ·10 - NIST Code Comparison

4.2 Comparison of BOCA to NEHRP


BOCA did not adopt the changes to the soil factors and seismic performance categoriesintroduced in NEHRP. The C. and Cv factors included in NEHRP result in highercalculated seismic forces for soil profiles C, D, and E, especially in regions of lowseismicity. Although the new factors result in slightly lower forces for soil profile A andequal forces in soil profile B, the documents are judged not equivalent with regard to soilfactors.

BOCA has similar, or more stringent, requirements regarding testing and inspection.Thus, the documents are judged equivalent with regard to inspection.


For calculation ofseismic forces for structural components, BOCA did not adopt thechanges introduced in NEHRP. The C. and Cv factors included in NEHRP result inhigher calculated seismic forces for very soft soils, especially in regions oflowseismicity. Thus, NEHRP is more stringent than BOCA and these sections are notequivalent.


For calculation of seismic forces for architectural, mechanical, and electrical components,BOCA did not adopt the changes introduced in NEHRP. The new formulas result inhigher forces for nonstructural components. Thus, NEHRP is more stringent than BOCAand these sections are not equivalent.


Foundation design requirements in BOCA have been expanded, providing additionaldesign requirements such as footing design, piles, and foundation and retaining walls.Thus, BOCA is more stringent than NEHRP and these sections are judged equivalent.


Both documents reference the same AISC standards without significant modification.Changes made to NEHRP either already existed in BOCA or were also changed inBOCA. Since both documents reference the same standard, BOCA and NEHRP areequivalent with regard to steel structure design requirements.

BOCA - 11 - NIST Code Comparison


Both documents adopt ACI 318, however, BOCA did not adopt NEHRP modifications toACI dealing with requirements for precast concrete frames. In addition, BOCA did notadopt NEHRP changes regarding strength and failure ofanchors. Thus, the documentsare judged equivalent with regard to concrete structure design requirements except forprecast concrete frame systems and strength and failure of anchors.


There are no provisions in BOCA regarding the design ofcomposite lateral forceresisting systems. While BOCA does not prohibit composite design explicitly, it is silenton an approach to take to design a structure with a composite lateral-foree-resistingsystem. Thus, NEHRP is more stringent with this type of structure and these documentsare judged not equivalent with regard to structures with composite lateral force resistingsystems.


Regarding design ofmasonry structures, NEHRP has developed its own strength designguidelines while BOCA has adopted ACI 530. ACI 530, however, uses working stressdesign provisions and modifies them to fit strength design guidelines. In comparingNEHRP with ACI 530, the strength checks are roughly similar, although they are notdirectly comparable. While working stress design uses allowable values and safetyfactors, and strength design uses load factors and ultimate strengths, neither procedure isexpected to provide results that are substantially different from the other. The detailingchecks and design parameters are also similar, but the parameters NEHRP sets are morestringent, such as smaller limits on maximum size ofreinforcement, exclusion ofbundling ofreinforcing bars, and longer hook development lengths in tension. Thus, thetwo sections are not equivalent in terms ofdetailing requirements. In summary, the twochapters are judged equivalent in intent, but are judged not equivalent in terms ofdetailing requirements and design parameters.


Both BOCA and NEHRP adopted 1991 National Design Specification for WoodConstruction (NDS) by AFPA without modifications. However, BOCA is morerestrictive in the use of certain materials, especially particleboard. Since BOCA isslightly more restrictive, the two documents are judged equivalent with regard to wooddesign requirements.

BOCA -12 - NIST Code Comparison

4.3 Conclusions Regarding BOCA

The 1996 BOCA had relatively few changes regarding seismic and material designprovisions. The sections in which the 1996 BOCA and 1994 NEHRP Provisions arejudged not equivalent are as follows:

• Seismic design values for structures

• Seismic design values for nonstructural components

• Precast concrete frame design requirements

• Strength and failure of concrete anchors

• Composite lateral force resisting systems and element design requirements

• Masonry detailing requirements and design parameters

While the design provisions for most major structural materials including steel, concreteand wood are essentially equivalent, the differences in seismic design values will result ina higher level of safety for structures designed using the NEHRP Provisions. The 1996BOCA and the 1994 NEHRP are therefore judged not equivalent.


5.0 COMPARISON OF 1997 USC TO 1994 NEHRP

Previous reports concluded that the 1994 UBC and the 1991 NEHRP Provisions weresubstantially equivalent. Since that time, changes have occurred in both documentswhich mayor may not be equivalent. This section summarizes the changes and makes acomparison between the current versions ofboth documents. Further documentation ofchanges and detailed side-by-side comparisons are contained in Tables 2A and 2B.

5.1 Overview of USC Provisions

The International Council ofBuilding Officials (leBO) assembles the Uniform BuildingCode (UBC). The seismic provisions are based on the SEAOC Blue Book which ispublished by the volunteer efforts of the Structural Engineers Association ofCalifornia.The stated intent ofthe code is to provide minimum standards to safeguard life or limb,health, property and public welfare.

Seismicity maps are used to assess the seismic hazard ofa particular region, and forcesand seismic design requirements are increased with increased seismic hazard. Higherlevels ofperformance are obtained by· increasing the design base shear through the use ofan importance factor (I). In the base shear equation, a factor (R), which accounts forsystem response and ductility, reduces the ground motion to a design level. The designbase shear varies with lIT, where T is the period of the structure.

The changes between the 1994 and the 1997 editions of the code are summarized below.Chapters 16 through 19, and 21 through 23 in the 1997 code are included in thiscompanson.

The UBC seismic design provisions were substantially revised in the 1997 edition. Thedesign basis was changed from allowable stress to strength based. Additional variableswere added to the base shear equation to consider distance to seismic source, seismicsource type and new soil profiles. A new simplified static procedure was added for useon certain simple buildings. Earthquake forces are now a combination of horizontal andvertical loads. The horizontal load is multiplied by a redundancy factor that penalizesnonredundant buildings. The maximum inelastic response displacement is calculatedusing a ductility factor for the system.

The formulas for calculating loads on nonstructural elements were revised. Responsecoefficients for the elements are included and the vertical location ofthe equipment in thebuilding is now a consideration. To match the measured response in buildings in recentearthquakes, the loads that result from the new equations are generally higher. Newrequired design loads for anchorage to flexible diaphragms have been given.

The materials chapters did not undergo substantial changes.

UBC -14- NIST Code Comparison

Comparisons between the substantial changes in each document are summarized in thefollowing section. The comparisons are arranged according to 1994 NEHRP chapters.For a more detailed and inclusive comparison, see Tables 2A and 2B.

5.2 Comparison of USC to NEHRP

5.2.1 Chapter 1: General Provisions (and Testing & Inspection)

The soil classifications in the 1997 UBC were revised to match the 1994 NEHRPProvisions. Therefore, the soil types are equivalent.

Both documents introduced new seismic coefficients. Other than seismic zone 4 nearfield effects in UBC, the coefficients are the same. Since the near source factors areintended to equate UBC with revised seismicity maps in 1997 NEHRP, and the factorswill only increase the coefficients, UBC is more stringent and the documents are judgedequivalent with regard to seismic coefficients.

In UBC, continuous special inspection is required for various items unless periodicinspection is allowed by project plans and specifications and approved by the buildingofficial. NEHRP specifically outlines the requirement for continuous or periodic specialinspection. Comparison between the documents was based on an assumption ofcontinuous special inspection in UBC. In the case where periodic special inspection isallowed, provisions in NEHRP may be more stringent. NEHRP has provisions forspecial inspection ofwood, architectural, mechanical and electrical components whichUBC does not. Since the inspection provisions are in place, and use ofthe provisions canbe implemented at the discretion ofthe design professional, UBC is judged equivalent inthis regard.

usc -15 - NIST Code Comparison


With the change to strength design in UBC, a direct comparison ofthe documents ispossible. The base shear formulas in the documents are similar. System ductility factors(R), however, are not necessarily the same in both documents and there is no consistenttrend toward higher or lower values in either document. To match higher seismicity nearactive fault zones that is included in the 1997 NEHRP, near field factors, which canincrease the base shear, have been included in UBC. Importance factors, which can alsoincrease the base shear, are included in UBC but not in NEHRP. Another difference isthe dependence on the building period. The base shear is proportional to 1fT in UBC andis proportional to IfT213 in NEHRP. Therefore, for buildings with a period greater than 1second, with all other variables being equal, NEHRP loads will be larger and thedocuments are not equivalent for long period structures. With near field effects andimportance factors, UBC loads will generally be larger in high seismic zones and thedocuments are judged equivalent in this regard. Therefore, the documents are judgedequivalent in structural design, criteria, analysis and procedures with the exception oflong period structures.

UBC added a simplified static procedure which allows a simplified base shear calculationfor certain structures. Although NEHRP does not have a simplified static procedure, theUBC formula results in loads that are larger than the equivalent lateral static forceprocedure, so UBC is more stringent and the documents are judged equivalent withregard to simplified base shear.

Since the load combinations in both documents are based on ASCE 7, they areequivalent. Both documents include a vertical earthquake load that depends on the deadload ofthe structure. The horizontal earthquake load in UBC is multiplied by aredundancy factor. The redundancy factor can never be less than 1 and can be as high as1.5. UBC also includes near field and importance factors on the vertical earthquakeloads. These factors may increase but not decrease the loads. Therefore, the earthquakeload combination factors in UBC will always be greater than or equal to NEHRP. Thus,the documents are judged equivalent with regard to load combinations.

The drift limits prescribed by NEHRP are more stringent than UBC. Drift is usually ameasure ofdamage, not life safety, and is usually only a concern in frame buildings.Therefore, with respect to the life-safety performance level, the documents are equivalentin intent, but not equivalent in design values and damage control. For higherperformance levels, UBC evaluates drift at higher force levels, and NEHRP also usesmore restrictive limits for higher performance. Therefore, the documents are equivalentin intent but not in drift design values.


To calculate inelastic drift, both documents amplify the design level deflections. NEHRPuses a deflection amplification factor and UBC uses a multiple ofthe ductility factor.There is no consistent trend toward higher or lower values in either document. Thus, thedocuments may be judged to be essentially equivalent in calculating inelastic drift.

The provisions for seismically isolated structures are equivalent in the documents. Inrequiring a dynamic analysis, NEHRP is more stringent. However, since the scaling ofbase shear to static levels is allowed, the design force levels will be equivalent, and thedocuments are judged equivalent in this regard.

The requirements for nonbuilding structures are equivalent. UBC does not containrequirements for passive energy dissipation systems. Since the section is located in anappendix in NEHRP, the provisions are just an introduction to the system. Therefore, thedocuments may be judged to be equivalent.


The formulas used to calculate the load on nonstructural components are similar in bothdocuments. Both documents revised the formula to depend on system amplification,flexibility and the vertical location of the equipment in the building. UBC has near fieldfactors in seismic zone 4 which may increase the load. The importance factors inNEHRP are related to the importance ofthe component for safety. The importancefactors in UBC tend to depend on the importance ofthe structure that the component islocated in rather than the importance of the component. Therefore, the two documentsare judged equivalent for architectural, mechanical, and electrical component designrequirements with the exceptions that follow.

The loads on parapets are higher in NEHRP. The response factor for parapets in NEHRPis halfof that in UBC and the importance factor for parapets is 50% higher, resulting insubstantially higher design forces for parapets.

New requirements for anchorage to flexible diaphragms are included in UBC. UBCrequires a 50% increase in loads when there is a connection to a flexible diaphragm,whereas NEHRP requires a 100% increase in loads in the center half ofa flexiblediaphragm span. Thus, with all other variables being equal, loads produced by NEHRPwill be larger than UBC.

NEHRP contains additional requirements for bracing nonstructural items such assuspended ceilings and access floors that are not included in UBC.


The foundation design requirements may be judged to be essentially equivalent. UBCadded requirements relating to expansive soils, post-tensioned slabs and minimumamounts ofreinforcement that are not in NEHRP.


NEHRP requires ties between spread footings whereas UBC does not. This is the onlyissue in the foundation design requirements that the documents are not strictly equivalent.This issue is not considered to have a significant impact on the safety ofa design, thus thetwo documents are judged substantially equivalent with regard to foundationrequirements.


Both documents reference Seismic Provisions for Structural Steel Building, Load andResistance Factor Design and Allowable Stress Design, all by AISC. Since these formthe basis ofthe design provisions, the documents are essentially equivalent in designprocedures. Modifications that were made to the references are essentially equivalent.

UBC included a new section on the requirements for special truss moment frames that isnot included in NEHRP making it more restrictive. Thus, the two documents are judgedequivalent with regard to steel design requirements.


Although both documents reference ACI 318 for design provisions, NEHRP referencesan earlier version. Since a later version ofACI 318 may be assumed to be at leastequivalent to, if not better than, the older version, UBC is more stringent. Therefore, thedocuments are judged equivalent with regard to concrete design requirements with theexceptions that follow.

Both documents added provisions for precast and plain concrete elements. Since NEHRPincludes requirements that are not in UBC, the documents are not equivalent with regardto precast and plain concrete.

The application limits for concrete moment frames are more stringent in NEHRP.NEHRP requires that moment frames on soil profile type E or F with seismicperformance category (SPC) B be an intermediate moment frame. SPC B tends to be in alower seismic zone than the zones corresponding to requirements for intermediate framesin the UBC. Therefore, the documents are not equivalent in the application limits forconcrete moment frame construction.



In the 1994 edition ofNEHRP, composite lateral force resisting systems are specificallyaddressed, and a new chapter was added. UBC does not specifically address compositesystems, but allows them as long as they are designed using well established principles ofmechanics. The composite system chapter in NEHRP mainly references other materialssections but also includes other requirements. The references that NEHRP uses are alsoreferenced in UBC. Since UBC does not specifically address composite systems in thedetail that NEHRP does, the documents are judged not equivalent with respect tocomposite systems. However, equivalence could be met if the user were to adopt thespecific provisions of the composite systems chapter in NEHRP.


With the change in emphasis to strength based design in NEHRP, the design basis in thedocuments is equivalent.


Both documents reference the 1991 National Design Specification for WoodConstruction (NDS) by AFPA for wood design. There were no substantive changes tothe portion of the wood design provisions in either document, therefore, the twodocuments are judged equivalent with regard to wood design requirements with theexceptions that follow.

In NEHRP, the limit for conventional construction is based on seismic performancecategory and number of stories in the building. UBC bases conventional constructionlimits on the type ofoccupancy, without regard to number of stories or seismic zone.With regard to residences, NEHRP is more stringent since UBC allows all 1-3 storyresidences to be constructed ofconventional construction, whereas the number ofstoriesin NEHRP is limited by the seismic performance category. With regard to standardoccupancy structures, UBC is more stringent since the structure is limited to a singlestory whereas in NEHRP, depending on the seismic performance category, a highernumber of stories may be allowed. The required braced wall spacing is more stringent inNEHRP.

NEHRP does not allow any material other than structural use panels to resist earthquakeloads whereas UBC allows other materials. Therefore, NEHRP in general is somewhatmore stringent for residential construction, and the documents are not equivalent in thisregard.


5.3 Conclusions Regarding USC

The 1997 UBC was substantially revised to utilize a strength based design approach. Theseismic design basis change in UBC allowed a more direct comparison of the documents.The 1997 UBC and 1994 NEHRP are judged equivalent in intent and essentiallyequivalent in design values with the following exceptions:

• Design base shear for long period buildings without near field and importancefactors

• Drift limits

• Design loads on parapets

• Design loads for anchorage to flexible diaphragms


• Application limits for intermediate concrete moment frames

• Wood conventional construction limits for residences

• Bracing requirements for access floors and suspended ceilings

• Requirements for precast and plain concrete

usc -20- NIST Code Comparison

6.0 COMPARISON OF 1997 SSC TO 1994 NEHRP

Previous reports concluded that the 1994 SBC and the 1991 NEHRP Provisions weresubstantially equivalent. Since that time, changes have occurred in both documentswhich mayor may not be equivalent. This section summarizes the changes and makes acomparison between the current versions of both documents. Further documentation ofchanges and detailed side-by-side comparisons are contained in Tables 3A and 3B.

6.1 Overview of SSC Provisions

The Southern Building Code Congress International (SBCCI) assembles the SBCCIStandard Building Code (SBC). The stated intent ofthe code is to serve as acomprehensive regulatory document to guide decisions aimed at protecting the public'slife, health, and welfare in the built environment. Since 1994, SBC has incorporated theNEHRP Provisions for seismic design. Thus, the methodology ofthe code is the same asNEHRP. It uses a strength-based approach, the same seismicity maps, the same seismicperformance categories, the same R values, and the seismic forces vary with the inverseofT2

/3

.

The changes between the 1994 and 1997 editions ofthe SBC are summarized below.Chapters 16 through 19, and 21 through 23 in the 1997 code are included in thiscompanson.

Few changes were made to formulas calculating seismic forces for structural,architectural, mechanical and electrical components. These sections have remainedessentially the same from the 1994 to the 1997 edition.

Few changes were made to provisions regarding foundation design requirements. Thefoundation wall section was the only section that was modified. It was rewritten toincorporate ACI 530/ASCE 5/TMS 402-95 and ACI 318-95.

The materials sections changed to the extent that SBC has adopted the most currentstandards with few modifications. SBC refers to AISC and AISI for steel, ACI forconcrete and masonry, and AFPA for wood. SBC, however, included new restrictions onthe use of particleboard in subflooring and roof sheathing in the wood section.


ssc - 21 - NIST Code Comparison

6.2 Comparison of SSC to NEHRP


SBC did not adopt the changes to the soil factors and seismic performance categoriesintroduced in NEHRP. The Ca and Cv factors included in NEHRP result in highercalculated seismic forces for soil profiles C, D, and E, especially in regions oflowseismicity. Although the new factors result in slightly lower forces for soil profile A andequal forces in soil profile B, the documents are judged not equivalent with regard to soilfactors.

SBC has similar requirements regarding testing and inspection or structural components.However, SBC did not incorporate testing and inspection changes made to thearchitectural, electrical, and mechanical components. Thus, two sections are judgedequivalent with regard to structural components and not equivalent for architectural,electrical, and mechanical components.


For calculation of seismic forces for structural components, SBC did not adopt thechanges introduced in NEHRP. The Ca and Cv factors included in NEHRP result inhigher calculated seismic forces for very soft soils, especially in regions oflowseismicity. Thus, NEHRP is more stringent than SBC and these sections are notequivalent.


For calculation of seismic forces for architectural, mechanical, and electrical components,SBC did not adopt the changes introduced in NEHRP. The new formulas result in higherforces for nonstructural components. Thus, NEHRP is more stringent than SBC andthese sections are not equivalent.


Few changes were made to foundation design requirements. In the SBC, the section onfoundation walls was rewritten to incorporate ACI 530/ASCE 5/TMS 402-95 and ACI318-95. The documents are judged to be equivalent with regard to foundation designrequirements.

SBC -22 - NIST Code Comparison


Both documents reference the same AISC and AISI standards without significantmodification. Changes made to NEHRP either already existed in SBC or were alsochanged in SBC. In addition, SBC added requirements for cold-formed steel stud-wallsystems that are more stringent than those in NEHRP. Since both documents referencethe same standards, SBC and NEHRP are equivalent with regard to steel structure designrequirements.


Both documents adopt ACI 318, however, SBC did not adopt NEHRP modifications toACI dealing with requirements for precast concrete frames. In addition, SBC did notadopt NEHRP changes regarding strength and failure ofanchors. Thus, the documentsare judged equivalent with regard to concrete structure design requirements except forprecast concrete frames and strength and failure of anchors.


There are no provisions in SBC regarding the design ofcomposite lateral force resistingsystems. While SBC does not prohibit composite design explicitly, it is silent on anapproach to take to design a structure with a composite lateral-foree-resisting system.Thus, NEHRP is more stringent with this type ofstructure and these documents arejudged not equivalent with regard to structures with composite lateral force resistingsystems.


Regarding design of masonry structures, NEHRP has developed its own strength designguidelines while SBC has adopted ACI 530. ACI 530, however, uses working stressdesign provisions and modifies them to fit strength design guidelines. In comparingNEHRP with ACI 530, the strength checks are roughly similar, although they are notdirectly comparable. While working stress design uses allowable values and safetyfactors, and strength design uses load factors and ultimate strengths, neither procedure isexpected to provide results that are substantially different from the other. The detailingchecks and design parameters are also similar, but the limits NEHRP sets are morestringent, such as smaller limits on maximum size ofreinforcement, exclusion ofbundling of reinforcing bars, and longer hook development lengths in tension. Thus, thetwo sections are not equivalent in terms ofdetailing requirements. In summary, the twochapters are judged equivalent in intent, but are judged not equivalent in terms ofdetailing requirements and design parameters.

SSC -23 - NIST Code Comparison


Both SBC and NEHRP adopted 1991 National Design Specification for WoodConstruction (NDS) by AFPA without modifications. However, SBC is more restrictivein the use ofcertain materials, especially particleboard. Since SBC is slightly morerestrictive, the two documents are judged equivalent with regard to wood designrequirements.

6.3 Conclusions Regarding SSC

The 1997 SBC had relatively few changes regarding seismic and material designprovisions. The sections in which the 1997 SBC and 1994 NEHRP Provisions are judgednot equivalent are as follows:

• Seismic design values for structures

• Seismic design values for nonstructural components

• Precast concrete frame design requirements

• Strength and failure ofconcrete anchors

• Inspections ofnonstructural components


• Masonry detailing requirements and design parameters

While the design provisions for most major structural materials including steel, concreteand wood are essentially equivalent, the differences in seismic design values will result ina higher level ofsafety for structures designed using the NEHRP Provisions. The 1997SBC and the 1994 NEHRP are therefore judged not equivalent.

SBC - 24- NIST Code Comparison

7.0 COMPARISON OF ASCE 7-95 TO 1994 NEHRP

Previous reports concluded that the ASCE 7-93 and the 1991 NEHRP Provisions weresubstantially equivalent. Since that time, changes have occurred in both documentswhich mayor may not be equivalent. This section summarizes the changes and makes acomparison between the current versions ofboth documents. Further documentation ofchanges and detailed side-by-side comparisons are contained in Tables 4A and 4B.

7.1 Overview of ASeE 7 Provisions

The American Society ofCivil Engineers (ASCE) assembles the Minimum Design Loadsfor Buildings and Other Structures (ASCE 7). This standard provides minimum verticaland lateral load requirements for the design of buildings and other structures that aresubject to building code requirements. Model building codes will sometimes referenceASCE 7 for the determination ofloads.

ASCE 7 contains all elements ofa code, and for provisions unrelated to the determinationof loads, ASCE 7 adopts NEHRP provisions with some revisions. The Appendix inASCE 7 contains supplemental seismic provisions relating to quality assurance,foundation design, and structural materials.

Seismicity maps are used to assess the seismic hazard of a particular region, and forcesand seismic design requirements are increased with increased seismic hazard. Similar toNEHRP, the seismic performance category ofa structure, which is based on occupancyas well as the seismicity, determines the level ofdetailing and design requirements. Theseismic performance category is used to obtain higher levels ofperformance, however, itdoes not influence the force level. In the base shear equation, a factor (R) which accountsfor system response and ductility, reduces the ground motion to a design level. Thedesign base shear varies with IIT2I3, where T is the period ofthe structure.

The changes between the 1993 and the 1995 editions ofthe standard are summarizedbelow. Chapters 1 through 9, and the Appendix in the 1995 standard are included in thiscomparison.

The 1993 edition ofthe standard adopted the 1991 NEHRP Provisions and subsequently,the 1995 edition adopted the 1994 NEHRP Provisions. Therefore, much ofthe changesthat have occurred in ASCE 7 are similar to the changes that occurred in NEHRP.Changes related to the determination of loads, other than earthquake, were notdocumented since the changes to NEHRP were judged to be not significant.

In the materials sections, updated versions ofthe reference standards were used. Thesupplementary masonry provisions in the appendix were removed.

ASCE7 - 25- NIST Code Comparison


7.2 Comparison of ASCE 7 to NEHRP


ASCE 7 contains four seismic hazard exposure groups, whereas NEHRP has three. Thetwo lowest hazard groups ofASCE 7 are encompassed by the lowest hazard group inNEHRP. In the determination of seismic performance category, ASCE 7 groups the twolowest hazard groups together. Thus, there is no implication to having a different numberofgroups. Therefore, the documents are judged equivalent with respect to generalprovisions with the exceptions that follow.

ASCE 7 requires quality assurance provisions for other designated seismic systems toapply to a larger number of seismic performance categories. However, ASCE 7 onlyrequires the quality assurance provisions to apply to components with an importancefactor of 1.5, whereas NEHRP does not have a similar specification. Therefore, NEHRPis more stringent for quality assurance provisions for other designated seismic systems.

ASCE 7 requires special inspection for the placement ofconcrete in deep foundationswhereas NEHRP requires it for all foundations. Therefore, NEHRP is more stringent forother types of foundations, and the sections are not equivalent.


Similar to NEHRP, ASCE 7 made changes to the seismic coefficients used in the baseshear equations. Therefore, with regard to structural design, criteria, analysis, andprocedure, the documents are judged to be equivalent with the exceptions that follow.

NEHRP references the previous version ofASCE 7 for load combinations. In the newversion ofASCE 7, fluid, soil and self-straining forces are not considered in combinationwith earthquake and wind forces, and in the current edition ofNEHRP they are. In thiscase, the documents are judged to be not equivalent.

The drift limits prescribed for masonry buildings in NEHRP are more stringent thanASCE 7. Therefore, the documents are judged to be not equivalent with respect tomasonry buildings.

ASCE7 -26 - NIST Code Comparison


The formulas used to calculate the load on nonstructural components are similar in bothdocuments. The formula was revised in both documents to depend on systemamplification, flexibility and the vertical location ofthe equipment in the building. Bothdocuments have the same importance factor and essentially the same response factors.Thus, the documents are judged to be equivalent with regard to architectural, mechanical,and electrical components design requirements with the exceptions that follow.

Powder-actuated fasteners are not allowed in NEHRP for seismic performance categoriesD and E, whereas ASCE 7 does not specifically disallow it. Therefore NEHRP is morestringent in prohibiting their use, and the documents are judged not equivalent withrespect to powder-actuated fasteners.

The force requirements are higher in NEHRP for exterior wall panel connections. Thus,the documents are judged not equivalent in this regard.


The only difference that occurs between the documents with respect to foundation designis the load used to design foundation ties. While the design load will be larger in NEHRPwhen soft soil conditions are present, both documents will produce structures withfoundation ties. Thus, with respect to foundation design the documents are judged to beessentially equivalent.


Both documents reference the same AISC standards with some modifications. Themodifications made in each document are equivalent. Thus, the documents are judgedequivalent with respect to steel structure design requirements.


Although both documents adopt ACI 318, ASCE 7 did not adopt NEHRP modificationsregarding precast concrete frames and strength and failure ofanchors. Thus, thedocuments are judged equivalent with regard to concrete structure design requirementsexcept for precast concrete frames and strength and failure ofanchors.

ASCE7 - 27- NIST Code Comparison


There are no provisions in ASCE 7 regarding the design ofcomposite lateral forceresisting systems. While ASCE 7 does not prohibit composite design explicitly, it issilent on an approach to take to design a structure with a composite lateral-foree-resistingsystem. Thus, NEHRP is more stringent with this type of structure and these documentsare judged not equivalent with regard to structures with composite lateral force resistingsystems.


Regarding design ofmasonry structures, NEHRP has developed its own strength designguidelines while ASCE 7 has adopted ACI 530. ACI 530, however, uses working stressdesign provisions and modifies them to fit strength design guidelines. In comparingNEHRP with ACI 530, the strength checks are roughly similar, although they are notdirectly comparable. While working stress design uses allowable values and safetyfactors, and strength design uses load factors and ultimate strengths, neither procedure isexpected to provide results that are substantially different from the other. The detailingchecks and design parameters are also similar, but the parameters NEHRP sets are morestringent, such as smaller limits on maximum size ofreinforcement, exclusion ofbundling ofreinforcing bars, and longer hook development lengths in tension. Thus, thetwo sections are not equivalent in terms ofdetailing requirements. In summary, the twochapters are judged equivalent in intent but are judged not equivalent in terms of detailingrequirements and design parameters.


Both documents reference 1991 National Design Specification for Wood Construction(NDS) by AFPA for wood design. The documents made equivalent changes to thestrength based design provisions, construction limitations for conventional constructionand shear panel sheathed with other sheet materials. Therefore, the documents are judgedequivalent with respect to wood structure design requirements.


7.3 Conclusions Regarding ASCE 7

ASCE 7 incorporates the 1994 NEHRP Provisions with some revisions for all items thatare not related to the determination ofloads. ASCE 7-95 and 1994 NEHRP are judged tobe equivalent in intent and design values with the following exceptions:

• Quality assurance provisions for other designated seismic systems

• Special inspection ofconcrete placement in foundations

• Masonry building drift limits, detailing requirements and design parameters

• Load combinations involving fluid, soil and self-straining forces

• Seismic application ofpowder-actuated fasteners

• Design load for the anchorage of exterior wall panels

• Precast concrete frame requirements

• Composite lateral force resisting system design requirements

• Strength and failure of concrete anchors


8.0 COMPARISON OF 1995 OTFDC TO1994 NEHRP

Previous reports concluded that the 1992 OTFDC and the 1991 NEHRP Provisions wereequivalent for conventional light frame dwellings two stories or 35 feet in heightmaximum, and townhouses ofwood frame construction in areas where Av < 0.5.Townhouses where Av 2: 0.05 were judged not equivalent. Since that time, changes haveoccurred in both documents which mayor may not be equivalent. This sectionsummarizes the changes and makes a comparison between the current versions of bothdocuments. Further documentation ofchanges and detailed side-by-side comparisons arecontained in Tables 5A and 5B.

8.1 Overview of OTFDC Provisions

The Council ofAmerican Building Officials (CABO) assembles the CABO One and TwoFamily Dwelling Code (OTFDC). CABO consists ofrepresentatives from the threemodel code organizations of the United States, International Conference ofBuildingOfficials (ICBO), Building Officials and Code Administrators International (BOCA), andSouthern Building Code Congress International (SBCCI). The model code organizationscreated CABO to provide consistency in code language throughout the three codes,Uniform Building Code (UBC), National Building Code (NBC), and Standard BuildingCode (SBC).

The scope ofthe One and Two Family Dwelling Code is limited to detached one- andtwo-family dwellings and one-family townhouses not more than three stories in height.The stated intent ofthe code is to provide minimum standards for the protection of life,limb, health, property, environment and for the safety and welfare ofthe consumer,general public, and the owners and occupants ofresidential buildings regulated by thecode. OTFDC is a prescriptive code which is intended to be used by builders rather thanengineers and architects. The code is intended primarily for conventional light frameconstruction and does not provide requirements for an engineered design. Additionally,the earthquake resistant provisions are minimal.

The changes between the 1992 and the 1995 editions ofthe code are summarized below.Chapters 1 through 8 in the 1995 code are included in this comparison.

The structural provisions chapters are arranged according to building components ratherthan building materials. The arrangement ofthe chapters was revised. OTFDC did notundergo any substantial changes to alter the general intent of the code. Additionaldetailing provisions were added and various tabulated values were revised.

OTFDC -30 - NIST Code Comparison

Since the scope of OTFDC is limited, only items in NEHRP that are within the scope ofOTFDC are used as a basis for comparison. Items in OTFDC that are not relevant to thecomparison to NEHRP were not documented. Structures exempt from the provisions ofNEHRP are one and two family dwellings with Ca<O.15 and one and two family wooddwellings not more than 2 stories with Ca>O.15 constructed in accordance with theprescribed conventional construction requirements. Therefore, the structures that arerelevant to the comparison are one and two family dwellings that are not more than threestories in height with C,.>O.15 and one and two family three story wood dwellings withCa>O.15. The conventional light frame construction provisions are also relevant to thecompanson.


8.2 Comparison of OTFDC to NEHRP


Quality assurance and special inspection provisions in OTFDC are not prescriptive. Theinspections that are commonly made in general practice are listed but requirements arenot laid out. Therefore, the special inspection requirements default to the localjurisdiction, and comparison between the documents can not be made.

Similarly, testing requirements are not prescribed by OTFDC and will default to the localjurisdiction. Therefore, with testing requirements are outside the scope ofOTFDC andthese requirements are not relevant to the comparison.

In OTFDC, additions, alterations or repairs to any structure shall conform to the presentcode, however, the existing structure is not required to conform to the requirements ofthepresent code. NEHRP states that an existing building addition shall be designed andconstructed so that the entire building conforms to the seismic force resistancerequirements for new buildings. Therefore, NEHRP is more stringent and the documentsare judged not equivalent with respect to additions, alterations and repairs.

OTFDC allows for modifications to be made to the code ifthere are practical difficultiesin conforming to the provisions. Since NEHRP does not have a similar provision thatallows for modifications, the sections are judged not equivalent. Therefore, with respectto general provisions, the documents are judged equivalent with the exceptions aspreviously stated.

OTFDC - 31 - NIST Code Comparison


All provisions relating to the calculation of seismic base shear are not relevant toOTFDC. Since OTFDC is a prescriptive document, seismic loads are not calculated.Therefore, most ofthe provisions in Chapter 2 are not relevant to the comparison.

In OTFDC, standard masonry wall anchorage requirements are given. In NEHRP, theload must be calculated and the anchorage designed. For low seismic zones, theanchorage that OTFDC prescribes appears to be sufficient and equivalent to NEHRP.However, at higher seismic zones, OTFDC does not require an increased anchoragerequirement and NEHRP requirements appear to exceed that ofOTFDC. Therefore, forhigh seismic zones, the masonry wall anchorage requirements are judged not equivalent.


NEHRP contains anchorage requirements for many components that are not within thescope of a one or two family dwelling. In these cases, the comparison is not relevant.Force calculations are also not relevant to the comparison since OTFDC is a prescriptivedocument.

OTFDC does not contain bracing requirements for items such as parapets, veneer, wallpanels and chimneys. NEHRP prescribes strict loads and the only exceptions are forcomponents in seismic performance category A and components with a low risk to lifesafety in seismic performance category B. Therefore, with respect to architectural,mechanical and electrical components design, the documents are judged not equivalent.


The documents are judged to be essentially equivalent with respect to foundation designrequirements. OTFDC prescribes geometric and material requirements for foundationsthat NEHRP does not.

NEHRP requires ties between footings whereas OTFDC does not. This is the only issuein the foundation design requirements that the documents are not strictly equivalent.Since this issue is not considered to have a significant impact on the safety ofa design,the documents are judged substantially equivalent with regard to foundationrequirements.



The only element of steel structure design that OTFDC covers is light framed walls andlight framed elements in roof-ceiling construction. NEHRP references design documentsfor light framed wall requirements, whereas the only requirement in OTFDC is thatelements in metal walls should be straight and free ofany defects. Therefore, NEHRP ismore stringent in the requirements oflight framed walls and the sections are judged notequivalent.


The concrete structure requirements in OTFDC relates to foundations and foundationwalls. All other elements relating to concrete are outside the scope ofOTFDC and arenot relevant to the comparison.

For seismic perfonnance category C in NEHRP, ACI 318.1 is referenced for minimumreinforcement around openings in basements and foundation walls. For seismic zones 0,1 and 2 in OTFDC, minimum thickness and allowable depths ofunbalanced fill are givenfor foundation walls. In addition, ACI 318.1 is a referenced standard in OTFDC.Therefore, the documents are judged equivalent for foundation walls in seismicperformance category C.

For seismic perfonnance categories D and E, NEHRP allows plain concrete basementswalls in one and two family dwellings three stories or less in height provided the wall isnot less than 7-1/2 inches thick and retains no more than 4 feet ofunbalanced fill. Forseismic zones 3 and 4 in OTFDC, the maximum amount offill allowed without requiringreinforcement is 4 feet and the minimum wall thickness is 8 inches. Therefore, thesections are judged equivalent in these cases. However, a structure in seismic zone 2may correlate to seismic perfonnance category D. In this case, the maximum allowableunbalanced fill is larger and reinforcement other than around openings is not required.Therefore, for structures in seismic zone 2 assigned to seismic perfonnance category D,the sections are judged not equivalent.


Composite steel and concrete structure design is outside the scope ofOTFDC. Therefore,the comparison of this chapter is not relevant.


The masonry structure requirements in OTFDC relates to foundations, foundation wallsand walls. All other elements relating to masonry are outside the scope of OTFDC andare not relevant to the comparison. Both documents reference ACI 530/ASCE 5/TMS402-91.


Since both documents reference the same standard, they are judged equivalent with theexceptions that follow. NEHRP includes some basic requirements relating to iS0lation ofmasonry partition walls from the basic structural system, roughened surface exposure,bundling ofbars and development ofreinforcement that are either not in OTFDC or notequivalent to it.


The conventional construction limitations are more stringent in NEHRP. NEHRPprescribes limitations in the number of stories for conventional construction according toseismic performance category. OTFDC allows all one and two family dwellings with nomore than 3 stories to follow prescriptive requirements similar to conventionalconstruction. NEHRP references OTFDC for conventional construction provisions,therefore, when conventional construction is permitted in NEHRP, the sections areequivalent. In the cases where conventional construction is not permitted in NEHRP, butis still within the scope of OTFDC, NEHRP requires an engineered structure and thedocuments are not equivalent. The structures within the scope ofOTFDC that are notpermitted to be conventional construction in NEHRP are 3 story SPC C, 2 and 3 storySPC D and all SPC E structures.

NEHRP requires the use ofbracing walls at a specified spacing. OTFDC requires let inbracing at a specified spacing. Therefore, NEHRP is more stringent and the sections arenot equivalent.

8.3 Conclusions Regarding OTFDC

NEHRP references OTFDC for conventional construction provisions. Therefore, for thestructures that NEHRP will allow conventional construction to be used, the documents arejudged equivalent. A disparity exists between the documents on which structures requirenonconventional construction. The structures that require an engineered design inNEHRP that are still within the scope ofOTFDC are 3 story SPC C, 2 and 3 story SPC D,and all SPC E structures. Since the earthquake resistance provisions are minimal inOTFDC, structures that require an engineered design in NEHRP are judged notequivalent. Other items in which the documents are judged not equivalent are as follows:

• Provisions for an existing building with an addition

• Masonry wall anchorage r~quirements

• Anchorage requirements for architectural elements

• Light framed metal wall requirements

• Masonry detailing

• Wall bracing requirements

• Limits in application of plain concrete in SPC D

OTFDC -34- NIST Code Comparison

9.0 CONCLUSIONS

In this report, the 1994 NEHRP Provisions are compared to five model building codesand standards including the 1996 BOCA, 1997 UBC, 1997 SBC, ASCE 7-95 and the1995 OTFDC. Preceding comparison reports judged the previous editions ofthese codessubstantially equivalent. Therefore, this study addressed only changes that have occurredbetween the current and previous editions ofeach model code and standard.

Changes between editions were documented, the impact of the changes were evaluated,and comparisons were made to the 1994 NEHRP Provisions. In the comparison, thedocuments were judged equivalent ifthe model code or standard provisions areequivalent to, or more stringent than, the requirements in NEHRP. The documents werejudged not equivalent ifthe provisions in NEHRP are more stringent than therequirements in the model building code or standard. In comparing the documents, onlychanges that were judged to be substantive were documented.

The results of the comparison are summarized below. Detailed conclusions regarding theequivalence of each model code or standard can be found in the appropriate section.

The 1996 BOCA was judged not equivalent due to differences in seismic design values.

The 1997 UBC was judged equivalent with some exceptions noted.

The 1997 SBC was judged not equivalent due to differences in seismic design values.

ASCE 7-95 was judged equivalent with some exceptions noted.

The 1996 OTFDC was judged equivalent when conventional construction is applicablebut not equivalent when engineered designs are required.

Conclusions -35 - NIST Code Comparison

REFERENCES

1. Assessment ofthe Seismic Provisions ofModel Building Codes. NIST GCR 91598.Council ofAmerican Building Officials, July 1992.

2. Comparison ofthe Seismic Provisions ofModel Building Codes and Standards to the1991 NEHRP Recommended Provisions. NIST GCR 95-674. Melvyn Green &Associates, Inc., May 1995.

References -36 - NIST Code Comparison

ed Provisions in BOCA and NEHRP JudI!!II!I!!l!!!!I

1994 NEHRP Changes 1996 BOCA Changes Comments

1.2 Scope This section lists structures that are 1610.1 This section allows the loads to be The 1996 BOCA deviatesexceptions to seismic design provisions. General determined from this section or significantly here due to the fact it didExceptions for one and two family ASCE 7-95. This change was not adopt the Ca and Cv factors useddwellings that were previously incorporated because BOCA did in the 1994 NEHRP. Thus, NEHRPdependent on Av, were revised to not adopt the Ca and Cv factors of is more stringent and the twodepend on a new coefficient Ca. the 1994 NEHRP or ASCE 7-95. sections are not equivalent.

The 1996 BOCA still uses the Aaand Av factors from the 1991NEHRP.

1.4.2 Seismic Six new soil profile types are defined in 1610.3.1 Site No Changes Since BOCA did not adopt theCoefficients this section where previously there were Coefficient changes made to NEHRP, using

4. Seismic coefficients Ca and Cv, which NEHRP will result in higher seismicdepend on soil profile and seismic zone, forces for soft soils, especially inare introduced in this section. Ca and Cv regions of low seismicity. Thus,replace AaS and Av in the 1991 NEHRP is more stringent and the twoprovisions. All provisions that were sections are not equivalent for softpreviously related to Av and Aa were soils.revised to reflect the new coefficients.

1.4.4 Seismic The seismic performance category for 1610.1.7 No Changes Since BOCA did not adopt thePerformance seismic hazard exposure group III Seismic changes made to NEHRP, NEHRP isCategory buildings with values of Av ranging from Performance more stringent. Thus, the two

0.15 to 0.20g was increased from C to D Category sections are not equivalent.to reduce the risk of collapse in essentialselVice buildings in regions of moderateseismicity.

1.6.2.4 The requirement for special inspection 1705.4.5 No Changes Since BOCA did not adopt theSpecial after the completion of placement of Inspection change made to NEHRP, NEHRP isInspection of prestressing steel was added. During more stringent. Thus, the twoPrestressed Prestressing sections are not equivalent.Concrete

BOCA ·37· NIST Code Comparison

1994NEHRP

1.6.2.8SpecialInspection ofArchitecturalComponents

Table 1A: Changed Provisions in BOCA and NEHRP Judged Not EquivalentChanges I 1996 BOCA I Changes I Comments

The criteria for requiring special 1705.10 Wall No Changes BOCA only requires specialinspection changed from the Panels and inspection in Seismic Performanceperformance criteria factor P, which Veneer Category E. Since NEHRP requiresdepends on seismic hazard exposure special inspection in Seismicgroup and the item to be braced, to the Performance Categories D and E it isseismic performance category, which more stringent. Thus, the twodepends on Av and seismic hazard sections are not equivalent.exposure group. Exceptions to periodicspecial inspection were added andadditional items requiring inspection wasadded.

1.6.2.9SpecialInspection ofMechanicaland ElectricalComponents

1.6.3.1.1Testing ofReinforcingSteel

BOCA

The criteria for requiring specialinspection changed from performancecriteria P to seismic performancecategory (see above). The itemsrequiring special inspection were revised.

The requirement to examine the certifiedmill test reports for each shipment ofreinforcing steel was defined to pertain tosteel used to resist flexural and axialforces in reinforced concreteintermediate and special moment framesand boundary members of reinforcedconcrete or reinforced masonry shearwalls.

1705.11Mechanicaland ElectricalComponents

No Changes

No equivalent section

- 38-

BOCA only requires specialinspection in Seismic PerformanceCategory E. Since NEHRP requiresspecial inspection in SeismicPerformance Categories C, D and E,it is more stringent. Thus, the twosections are not equivalent.

Since BOCA has no provisions,NEHRP is more restrictive. Thus, thetwo sections are not equivalent.


1994 NEHRP



Where ASTM A615 reinforcing steel is No equivalent section Since BOCA has no provisions,used to resist earthquake-induced NEHRP is more restrictive. Thus, theflexural and axial forces in special two sections are not equivalent.moment frames and in wall boundaryelements of shear walls in buildings ofseismic performance category D and E,verify that the requirements of Sec.21.2.5.1 of Ref. 6-1 have been satisfied.


1.6.3.4.3Testing ofStructuralSteel

Where ASTM A615 reinforcing steel is tobe welded, verify that chemical testshave been performed to determineweldability in accordance with Sec. 3.5.2of Ref. 6-1.

ASTM A435 and ASTM A898 are addedcriteria on which to jUdge theacceptability of base metal thicker than1.5 in. that is subject to throughthickness weld shrinkage strains.





CHAPTER 2: STRUCTURAL DESIGN CRITERIA, ANALYSIS AND PROCEDURES

1994NEHRP

2.2.5.1.2Anchorage ofConcrete orMasonryWalls

2.3.2.1Calculation ofSeismicResponseCoefficient

Changes

Although there were no changes in thissection, the formula to calculate theanchorage force in section 3.1.3 wasrevised.

In calculating Cs, the seismic responsecoefficient, Cv replaces AvS and Careplaces Aa in the equations. Usingthese new coefficients, the base shear islowered for structures on rock but isincreased for structures on soft soils.The base shear of a structure is V=CsW.

1996 BOCA

1610.3.6.1.2Concrete orMasonry WallAnchorage


No Changes

No Changes

Changes Comments

Since BOCA did not adopt thechange to the anchorage force, thechange in NEHRP will result in ahigher anchorage force. Thus,NEHRP is more stringent and the twosections are not equivalent.

Since BOCA did not adopt thechange to the seismic responsecoefficient, NEHRP results in higherseismic forces for buildings on softsoils. Thus, NEHRP is morestringent and the two sections are noteqUivalent.

BOCA - 39- NIST Code Comparison

1994 NEHRP

2.6 Provisionsfor SeismicallyIsolatedStructures


This is a new section based on the 1994 No equivalent section BOCA has no specific provisions forUBC Appendix Chapter 16, Division III. seismically isolated structures. WhileThe provisions have been modified to BOCA does not prohibit this type ofconform to the strength based design design, it is silent on the approach toapproach and nomenclature ofthe take to design a seismically isolateddocument. structure. Therefore, NEHRP is more

restrictive and the two sections arenot equivalent.

2.6.2.3SeismicHazardExposureGroup

2.6.2.5.2EquivalentLateral ForceProcedure

2.6.2.5.3.3Site SpecificDesignSpectra

BOCA

All portions of the building shall beassigned a Seismic Hazard ExposureGroup.

The provisions for using the equivalentlateral force procedure are included inthis section.

The criteria that would require a sitespecific design spectra analysis isincluded in this section.




·40·

BOCA has no specific provisions forseismically isolated structures. WhileBOCA does not prohibit this type ofdesign, it is silent on the approach totake to design a seismically isolatedstructure. Therefore, NEHRP ismore restrictive and the two sectionsare not equivalent.

BOCA has no specific provisions forseismically isolated structures. WhileBOCA does not prohibit this type ofdesign, it is silent on the approach totake to design a seismically isolatedstructure. Therefore, NEHRP is morerestrictive and the two sections arenot equivalent.

BOCA has no specific provisions forseismically isolated structures. WhileBOCA does not prohibit this type ofdesign, it is silent on the approach totake to design a seismically isolatedstructure. Therefore, NEHRP ismore restrictive and the two sectionsare not equivalent.


1994NEHRP

2.6.6.2.8InspectionandReplacement


Access for inspection and replacement I INo equivalent section IBOCA has no specific provisions forofthe isolation system shall be provided. seismically isolated structures. While

BOCA does not prohibit this type ofdesign, it is silent on the approach totake to design a seismically isolatedstructure. Therefore, NEHRP ismore restrictive and the two sectionsare not equivalent.

2.6.9.3Determination of ForceDeflectionCharacteristics

2.6.9.4SystemAdequacy

2.7 ProvisionsforNonbuildingStructures

BOCA

This section includes a formula tocalculate the effective stiffness of anisolation system.

This section includes the criteria to judgeadequacy in test specimens.

This new section includes requirementsto design all self-supporting structures,other than buildings, bridges and dams,that are supported by the earth, thatcarry gravity loads, and that may berequired to resist the effects of anearthquake.




-41 -



BOCA has no specific provisions fornonbuilding structures. While BOCAdoes not prohibit this type of design,it is silent on the approach to take todesign a seismically isolatedstructure. Therefore, NEHRP ismore restrictive and the two sectionsare not equivalent.


ed Provisions in BOCA and NEHRP Jud


3.1 General The requirements for architectural, 1610.6 No changes Since BOCA did not revise thismechanical, and electrical components Architectural, section to include the new provisions,have been revised. The exceptions to Mechanical, NEHRP is more stringent and the twofollowing the provisions are included. and Electrical sections are not equivalent.

Componentsand Systems

3.1.3 Seismic Previously, lateral force calculations for 1610.6.3 This section added an exception to Since BOCA did not revise theForces architectural and mechanical/electrical Architectural seismic forces for architectural formulas, the NEHRP formulas will

equipment were separated. In the new Component component design of storage racks. result in higher seismic forces forprovisions, general formulas for all Design The formulas used are still from the nonstructural components. Thus,equipment are provided. The formulas 1610.6.4 1991 NEHRP. NEHRP is more stringent and the twodepend on Ca, importance factor ofthe Mechanical, sections are not equivalent.equipment, component amplification, Electricalresponse factors, and vertical location of Componentthe equipment in the building. and System

Design

3.1.4 Seismic This new section introduces formulas to No equivalent section Since BOCA has no provision,Relative calculate the relative displacement that NEHRP is more stringent. Thus, theDisplacement may occur between components. two sections are not equivalent.

3.1.5 New importance factors are introduced Table No Changes Since BOCA did not revise thisComponent which depend on the severity of failure of 1610.6.3 section, NEHRP is more stringent.Importance the component. Table Thus, the two sections are notFactor 1610.6.4 (1) equivalent..3.2.6 This new section outlines additional 1610.6.3.3 No Changes Since BOCA did not revise thisSuspended requirements for bracing suspended Ceilings section, NEHRP is more stringent.Ceilings ceilings. Design and construction Thus, the two sections are not

references and minimum clearances are equivalent.among the additional requirements.


1994 NEHRP

3.2.7 AccessFloors


This new section outlines additional No equivalent section Since BOCA has no provision,requirements for bracing access floors. NEHRP is more stringent. Thus, theThe weight used to calculate loads and two sections are not equivalent.the requirements for special accessfloors are included.

3.2.9 SteelStorageRacks


This new section outlines additionalrequirements for bracing steel storageracks. The weight used to calculate loadsand the response factor to design therack are included.

Extensive requirements for bracingvarious mechanical and electricalcomponents such as piping, elevators,and storage tanks are provided.

1610.6.4Mechanical,ElectricalComponentand SystemDesign


No Changes

Since BOCA has no provision,NEHRP is more stringent. Thus, thetwo sections are not equivalent.

Since BOCA did not revise thissection, NEHRP is more stringent.Thus, the two sections are notequivalent.

CHAPTER 4: FOUNDATION DESIGN REQUIREMENTS

1994NEHRP

4.4.3FoundationTies

BOCA

Changes

The design loads for foundation ties arerevised because of the change inseismic coefficients.

1996 BOCA

1810.2FootingSeismicTies

No Changes

-43 -

Changes Comments

The loads in NEHRP are larger whenCa is greater than 0.4, which occursin regions of high seismicity with softsoils. Since no change was made toBOCA, NEHRP is more stringentunder these conditions. Thus, thesections are not equivalent in highseismic zones on soft soils.


Chanaed Provisions in BOCA and NEHRP Jud

1994NEHRP

6.1.1.5

6.1.1.7

6.1.1.8

6.1.1.12

6.2.2 Strengthof Anchors

6.2.3 StrengthBased onTests

Changes

Requirements for connections of precastconcrete elements that emulate thebehavior of monolithic reinforcedconcrete construction were added.

Requirements for strong connections ofprecast concrete frames were added.

This section includes provisions forcalculating the probable capacities ofstructural elements in precast concreteframes.

This section contains additionalrequirements for concrete diaphragms.

A provision was added that states thatanchors shall be detailed so that theconnection failure is initiated by thefailure of the anchor steel rather than bythe failure ofthe surrounding concrete.

The strength reduction factor for anchorsshall be 0.8 when the anchor failuregovems in the majority ottests and 0.65when the concrete failure controls.

1996 BOCA

1903.1.1Modificationsto AC1318-95

1903.1.1Modificationsto ACI 318-95

1903.1.1Modificationsto ACI 318-95

1903.1.1Modificationsto AC1318-95

1913.1.2Strength ofAnchors

1913.1.2Strength ofAnchors

Changes

No equivalent modification




No Changes

No Changes

Comments

Since BOCA does not have thismodification, the modification resultsin NEHRP being more stringent.Thus, the two sections are notequivalent.




BOCA does not distinguish thestrength of anchors due to failuremode. NEHRP will provide a ductilityfailure mode, while BOCA may not.Thus, the two sections are notequivalent.

Since BOCA does not distinguish thestrength of anchors due to failuremode, there are no strength reducingfactors. Thus NEHRP is morestringent and the two sections are notequivalent.


1994NEHRP

6.2.4 StrengthBased onCalculations


The formula to calculate the tensile 1913.1.2.1 No Changes Since BOCA did not revise thestrength governed by concrete failure Strength in equations it will result in a higherwas revised. Two formulas which Tension calculated capacity when concretedepend on the spacing of the anchors failure governs. Thus, NEHRP isare given. more stringent and the two sections

are not equivalent.

6.2.4.3CombinedTension andShear

6.5.2 MomentFrames

The interaction equations to check thecapacity for a combination oftension andshear were revised. The result of thechange is less stringent interactionequations.

A new provision was added that statesthat moment frames on soil profile type Eor F with seismic performance categoryB shall be an intermediate momentframe.

1913.1.2.3CombinedTension andShear

No Changes


BOCA was more stringent than theprevious version of NEHRP.However, with the modifications toNEHRP, BOCA only has two ofthefour equations in NEHRP. Thus,NEHRP is more stringent and the twosections are not equivalent.

Since BOCA has no eqUivalentsection, NEHRP is more stringent.Thus, the two documents are notequivalent for seismic performancecategory Bmoment frames on soiltypes E and F.

CHAPTER 7: COMPOSITE STEEL AND CONCRETE STRUCTURE DESIGN REQUIREMENTS

1994 NEHRP

Chapter 7CompositeSteel andConcreteStructureDesignRequirements

BOCA

Changes

This new chapter presents design anddetailing requirements for compositestructures that are expected to providestructural toughness, ductility, strength,and stiffness equivalent to comparableconcrete and steel structures.

1996 BOCA Changes


-45 -

Comments

There is no equivalent sectionregarding composite design inBOCA. In addition, although notprohibiting composite design, BOCAis silent on any specific approach totake in designing a structure using acomposite lateral-force-resistingsystem. Therefore, NEHRP is morestringent and the sections are notequivalent.


1994 NEHRP

7.2 ReferenceDocuments


The reference documents are listed in I INo equivalent section ISince there is no equivalent sectionthis section. regarding composite design in

BOCA, NEHRP is more stringent.Thus, the sections are not equivalent.

7.4CompositeSystems

7.5CompositeMembers

7.5.1CompositeSlabs

7.5.2CompositeBeams

BOCA

Requirements to design compositesystems (partially restrained frames,ordinary moment frames, specialmoment frames, concentrically bracedframes, eccentrically braced frames,reinforced concrete walls composite withsteel elements and composite shearwalls) are in this section. The sectionoutlines the design requirements forindividual elements ofthe system.

This section lays out the requirements forstructural steel, reinforcing steel andconcrete. The requirements refer to thesteel and concrete codes.

The requirements for designingcomposite slabs are included in thissection.

Additional requirements for specialmoment frames are given as follows. Amaximum distance from the maximumconcrete compression fiber to the plasticneutral axis is given. Compressionelements that are fully encased by areinforced concrete cover (min. 2'~ donot need to meet the width-thicknessratio provided that concrete is confinedby hoop reinforcement in regions whereplastic hinges are expected to occur.





-46 -

Since there is no equivalent sectionregarding composite design inBOCA, NEHRP is more stringent.Thus, the sections are not equivalent.



Since there is no equivalent sectionregarding composite design inBOCA, NEHRP is more stringent.Thus, the sections are not eqUivalent.


td NEHRP Judaed Not EBOCAdPTable 1A: Ch .... .... .1994 NEHRP Changes 1996 BOCA Changes Comments

7.5.3 Encased This section references LRFD for the No equivalent section Since there is no equivalent sectionComposite design of encased composite columns. regarding composite design inColumns Additional requirements for seismic BOCA, NEHRP is more stringent.

performance category C, 0 and E are Thus, the sections are not equivalent.given. Most ofthe additional requireentsare related to concrete reinforcing.

7.5.4 Filled This section outlines the requirements for No equivalent section Since there is no equivalent sectionComposite filled composite columns. LRFD is regarding composite design inColumns referenced and additional requirements BOCA, NEHRP is more stringent.

are given for seismic performance Thus, the sections are not equivalent.categories 0 and E.

7.6 This section includes requirements for No equivalent section Since there is no equivalent sectionComposite connections in structures with composite regarding composite design inConnections or dual steel-concrete systems where BOCA, NEHRP is more stringent.

seismic loads are transferred. Thus, the sections are not equivalent.


Chanaed Provisions in BOCA and NEHRP Jud.s.uS_4.CI_lCi&S_CELESEI_CS_C.

1994 NEHRP

8.1 General

Changes

The masonry structure design approachwas changed from working stress designto limit states design.

1996 BOCA

2101.2SeismicRequirements

(2104.0SeismicRequirements)

Changes

This section incorporates ACI530/ASCE 5ITMS 402-95 in itsentirety. Modifications to thisreference were removed.

Comments

ACI 530/ASCE 5ITMS 402-95 didincorporate strength design fortheseismic provisions. Therefore, themethodology approach is the same.However, rather than develop aseparate set of strength designprovisions, the standard takes theexisting working stress designmethodology and uses load factors,phi factors, and a 3.325 increase ofallowable working stress values. Thedetailing provisions in the standardessentially remain the same. Incomparing ACI 530 and NEHRP, theformulas to calculate strengthcapacities appear to be equivalent,although NEHRP tends to be a bitmore restrictive. In the detailingprovisions, similar checks arerequired in both documents.However, NEHRP is more restrictivewith the parameters it sets, such asmaximum size of reinforcement,bundling of reinforcing bars, andhook development lengths in tension.Based on the comparison ofACI 530and NEHRP, NEHRP appears to bemore stringent. Thus, the sectionsare not equivalent.


1994 NEHRP

8.3.7 SeismicPerformanceCategory C

8.3.8 SeismicPerformanceCategory D


The screen wall requirements were 2101.2 BOCA uses ACI 530/ASCE 5fTMS ACI 530/ASCE 5fTMS 402-95 doesremoved. Requirements for walls Seismic 402-95 in its entirety. not have provisions for wallsseparated from the basic structural Requirements separated from the basic structuralsystem were added. The restriction on system. Thus, NEHRP is moreuse of structural clay nonload-bearing restrictive and the two sections arewall tile (ASTM C56) was removed. not equivalent.

The required roughened surface 2101.2 BOCA uses ACI530/ASCE 5fTMS ACI 530/ASCE 5fTMSO 402-95 doesexposure for concrete placement next to Seismic 402-95 in its entirety. not have provisions for roughenedmasonry that is not designed with a Requirements surface exposure for concreteseparation joint was increased from placement next to masonry. Thus,1/16" to 1/8". NEHRP is more restrictive and the

two sections are not equivalent.

8.4.3PlacementLimits forReinforcement

Bundling of bars is no longer allowed. 2101.2SeismicRequirements

BOCA uses ACI 530/ASCE 5fTMS IACI 530/ASCE 5fTMS 402-95 allows402-95 in its entirety. the use of bundled bars. Thus,

NEHRP is more restrictive and thetwo sections are not equivalent.

8.4.5Developmentof Reinforcement

The calculation of embedment length(Eq. 8.4.5.2) was modified. Arequirement for 6 inches of minimumembedment length for wire was added.The calculation of embedment length forhooks (Eq. 8.4.5.4.2) was modified. lapsplices are no longer allowed in plastichinge zones.


BOCA uses ACI 530/ASCE 5fTMS402-95 in its entirety.

Due to the equation parameters, adirect comparison was not possible.However, the equation in ACI530/ASCE 5fTMS 402-95 onlyconsiders the diameter of the bar andthe strength of steel. The equationsin NEHRP also take into accountclear cover and strength of masonry.Based on this, NEHRP may beconsidered more stringent and thetwo sections are not equivalent.

8.5.4 This section was rewritten to beDeformation consistent with the deformation criteriaRequirements .set forth in Chapter 2.



ACI 530/ASCE 5fTMS 402-95 doesnot contain deformation provisions,only strength provisions. Thus,NEHRP is more restrictive and thetwo sections are not eqUivalent.


1994NEHRP

8.6.2 DesignRequirementsof ReinforcedMasonryMembers


The critical strain ratio was reduced from 2101.2 BOCA uses ACI 530/ASCE 5fTMS ACI 530/ASCE 5/TMS 402-95 does0.003 to 0.002. The critical strain ratio, Seismic 402-95 in its entirety. not define a critical strain ratio. Thus,which occurs at the balanced condition, Requirements NEHRP is more stringent and the twois used to calculate the maximum sections are not equivalent.reinforcement ratio.

8.7.3 Designof ReinforcedMasonryMembers

8.11.2ConfinementofCompressiveStress Zone

8.11.3FlangedShear Walls

The equations to calculate shearstrength in both the masonry andreinforcing steel were modified (Eq.8.7.3.2-1,8.7.3.3).

The requirement for confinement waschanged from a strain limit to the plastichinge zone regions. The definition of aconfined compressive zone was added.

A requirement was added that states thatsolid units shall be laid in running bondand 50% of the masonry units at wallintersections shall be inter1ocked. Theeffective width of flange in compressionwas changed from 116 of the wall heightto 9 times the thickness of the web. Theeffective width of flange in tension waschanged from 1/3 of the wall height to3/4 of the wall height.

2101.2SeismicReqUirements






ACI 530/ASCE 5/TMS 402-95 usesone equation for calculating the shearcapacity, independent ofthe steelreinforcement provided. NEHRPuses separate equations forcalculating shear capacities ofmasonry and steel. Since NEHRP isthe more accurate of the twomethods, is may be considered morestringent. Thus, the two sections arenot equivalent.

ACI 530/ASCE 5/TMS 402-95 doesnot contain provisions for confinement of the compressive stress zone.Thus, NEHRP is more restrictive andthe two sections are not equivalent.

ACI 530/ASCE 5/TMS 402-95 doesnot contain provisions for flangedshear walls. Thus, NEHRP is morerestrictive and the two sections arenot eqUivalent.


Table 1A: Ch dP BOCA d NEHRP Judaed Not E t.1994 NEHRP Changes 1996 BOCA Changes Comments

8.12 Wall The requirement of where plastic hinges 2101.2 BOCA uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 doesFrames shall be formed was removed. Seismic 402-95 in its entirety. not contain provisions for wall

Requirements frames. Thus, NEHRP is morerestrictive and the two sections arenot equivalent.

8.12.4 A new restriction requires that actual 2101.2 BOCA uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 doesReinforce- yield strength shall not exceed 1.5 times Seismic 402-95 in its entirety. not contain provisions for wall framement the nominal yield strength. Requirements reinforcement. Thus, NEHRP is

more restrictive and the two sectionsare not equivalent.

8.12.5 Wall An additional restriction that the 2101.2 BOCA uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 doesFrame Beams reinforcement ratio shall be less than Seismic 402-95 in its entirety. not contain provisions for wall frame

0.15fmlfy was added. The maximum Requirements beams. Thus, NEHRP is morespacing of transverse reinforcement was restrictive and the two sections areincreased from 1/4 of the beam depth to not equivalent.1/2 of the beam depth.

8.12.6 Wall The limit of factored axial compression 2101.2 BOCA uses ACt 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 doesFrame force was changed from 0.30Anfm to Seismic 402-95 in its entirety. not contain provisions for wall frameColumns 0.15Anfm. The limit of minimum column Requirements columns. Thus, NEHRP is more

dimension was decreased from 32 restrictive and the two sections areinches to 24 inches. not equivalent.

8.12.7 Wall The definition of the dimension of the 2101.2 BOCA uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 doesFrame Beam- beam-column intersection was changed Seismic 402-95 in its entirety. not contain provisions for wall frameColumn from a multiple ofthe bar diameters to Requirements beam-column intersections. Thus,Intersection Eq. 8.12.7.1-1 and Eq. 8.12.7.1-2. A NEHRP is more restrictive and the

restriction that the shear stress shall not two sections are not equivalent.exceed 7 roots fm was added.

BOCA ·51 • NIST Code Comparison

ed Provisions in BOCA and NEHRP JudS.E_CSS_C__S.SLU_CXS_CELCSEI_CS_CSSLi.iE_CS_

1994NEHRP

9.9.1.2 ShearPanelsSheathed withother SheetMaterials

BOCA

Changes

Previously, light framed walls sheathedwith lath and plaster, gypsum sheathingboards, gypsum wallboard, or fiberboardsheets could be used to resistearthquake forces. Except inconventional construction, newprovisions do not allow sheet materialsother than structural-use materials to bepart of the seismic force resisting system.

1996 BOCA

2501.0GypsumBoard andPlaster

Changes

BOCA allows the use of gypsumboard and plaster to resist seismicforces in wood-framed buildings.

- 52-

Comments

Since the 1994 NEHRP does notallow the use ofgypsum board andsimilar materials to resist seismicforces at all, it is more stringent.Thus, the sections are not equivalentfor wood-framed buildings.


Table 1B: Changed Provisions in BOCA and NEHRP JUdged EquivalentCHAPTER 1: GENERAL PROVISIONS


1.6 Quality Quality assurance provisions now apply 1701.0 No Changes Since the quality assuranceAssurance to other designated seismic systems in General provisions is BOCA apply to all

seismic performance category D. categories, it is more stringent thanNEHRP. Thus, the two sections areequivalent.

1.6.2 Special No Changes 1705.1 This section added a special Since NEHRP has no exemptions,Inspection General exemption for Group U buildings BOCA is more restrictive. Thus, the

that are accessory to a residential two sections are equivalent.occupancy building.

1.6.2.1 The requirement for continuous special 1705.8 Pile No Changes Since BOCA already has theFoundation inspection for placement of concrete was Foundations changes made to NEHRP, the twoSpecial added. The requirement for continuous 1705.9 Pier sections are equivalent.Inspection special inspection for construction of Foundations

drilled piles and caissons was changedto periodic inspection. The requirementfor periodic inspection for placement ofreinforcing steel was added.

1.6.2.2.1 The requirement for periodic special 1705.4.2 No Changes BOCA requires special inspections ofSpecial inspection during and upon completion of Installation of reinforcing steel for all types ofInspection for reinforcing steel placement in Reinforcing construction. Thus. it is moreReinforcing intermediate concrete moment frames and restrictive than NEHRP and the twoSteel and concrete shear walls was added. Prestressing sections are equivalent.

The requirement for periodic special Steelinspection of the placement of steel inreinforced masonry shear walls andordinary moment frames was deleted.


1994 NEHRP

1.6.2.2.2SpecialInspection forReinforcingSteel

Table 1B: Changed Provisions in BOCA and NEHRP Judged EquivalentChanges I 1996 BOCA I Changes I Comments

The requirement for continuous special 1705.4.2 No Changes BOCA requires special inspections ofinspection during the welding of Installation of reinforcing steel for all types ofreinforcing steel was defined to pertain to Reinforcing construction. Thus, it is moresteel resisting flexural and axial forces in and restrictive than NEHRP and the twointennediate and special moment frames Prestressing sections are equivalent.of concrete, and in boundary members of Steelconcrete shear walls.

1.6.2.3SpecialInspection ofConcrete

1.6.2.6.1SpecialInspection ofStructuralSteel Welding

BOCA

The requirement for special inspectionduring and on completion oftheplacement of concrete for intennediateand special moment frames andboundary members of concrete shearwalls was added. The requirement forperiodic special inspection duringplacement of concrete in reinforcedconcrete frames and shear walls wasdeleted.


An exception to continuous specialinspection in lieu of periodic inspectionfor welds loaded to less than 50 percentof their design strength was added.

1705.4ConcreteConstruction

1705.4.1Materials

1705.3.3.2Welding

No Changes

This section was reworded inregards to weldability of reinforcement requirements. The sectionpreviously stated that weldability ofreinforcement that confonns toASTM A706 needed to meet certainrequirements. The section nowstates that weldability of reinforcement that does not confonn toASTM A706 needs to meet certainrequirements. This may have beena typo in the previous code.

No Changes

- 54-

BOCA requires special inspections ofconcrete for all types of construction(with some exceptions). Thus, it ismore restrictive than NEHRP and thetwo sections are equivalent.

Since the 1994 NEHRP has noprovisions, the 1996 BOCA is morerestrictive. Thus, the two sectionsare equivalent.

Since BOCA did not adopt thischange, it is more restrictive. Thus,the two sections are equivalent.


Table 1B: Ch dP BOCA d NEHRP Judaed E t1994 NEHRP Changes 1996 BOCA Changes Comments

1.6.2.6.2 Bolts in connections identified as not 1705.3.3 No Changes Since BOCA did not adopt theSpecial being slip-critical or subject to direct Erection change made to NEHRP, BOCA isInspection of tension need not be inspected for bolt more stringent. Thus, the twoStructural tension other than to ensure that the sections not equivalent.Steel Bolts plies of the connected elements have

been brought into snug contact.

1.6.2.7.1 The requirement for continuous special 2301.2 This section was added for Since both sections have added theSpecial inspection during field gluing operations Inspections installation ofwood framing same provision, the two sections areInspection of was defined to be for elements of the members. equivalent.Structural seismic force resisting system.Wood

1.6.2.7.2 The requirement for periodic special 2301.2 This section was added for Since both sections have added theSpecial inspection for nailing, bolting, anchoring, Inspections installation of wood framing same provision, the two sections areInspection of and other fastening was defined to members. equivalent.Structural pertain to all seismic components.Wood

1.6.3.1 The requirement for a sample at No equivalent section Since the NEHRP provision wasTesting of fabricator's plant and the testing of deleted, the two sections areReinforcing reinforcing steel used in certain equivalent.Steel applications was deleted.

No equivalent section 1705.12 This section was added Since the 1994 NEHRP has noSprayed provisions, the 1996 BOCA is moreCementitious restrictive. Thus, the two sections areand Mineral equivalent.FiberFireresistiveMaterials

No equivalent section 1705.13 This section was added Since the 1994 NEHRP has noExterior provisions, the 1996 BOCA is moreInsulation and restrictive. Thus, the two sections areFinish equivalent.Systems(EIFS)


ed Provisions in BOCA and NEHRP Judged Equivalent~

1994NEHRP Changes 1996 BOCA Changes Comments

2.2.2 New building frame systems, particular1y 1610.3.3 No Changes BOCA does not have any provisionsStructural relating to composite systems, were Structural related to the design of compositeFraming added. R and Cd values for ordinary Framing systems. In addition, although BOCASystems moment frames of reinforced concrete Systems does not prohibit composite design,

and intennediate moment frames of there are no provisions to design areinforced concrete were increased. composite structure by rational

analysis. Thus, the two sections arenot equivalent when dealing withcomposite structures. In otherstructures, however, BOCA has an Rvalue equal to or less than NEHRP'svalues. Thus, the sections areequivalent.

2.2.6 Load combinations are referenced to 1610.3.7 This section changed loading Since both documents reference theCombination ANSIIASCE 7-93 which differ from the Combination combinations to match ASCE 7-95. same standard, and BOCAof Load previously given combinations. In of Load However, rather than adopt the Ca references the most current edition ofEffects earthquake load combinations, the dead Effects and Cv factors, the Aa and Av the standard, the sections are

load factor is slightly higher but the live factors from ASCE 7-93 are equivalent.and snow load factors are typically lower. retained.The vertical earthquake loads depend onCa where they previously depended onAv. The new vertical loads will be lessfor soil profile A, equivalent for soil type Band in most cases they will be larger forsoil types C, D and E.

Table 2.2.7 The category for single story buildings in Table This table added allowable story Both codes have changed to reflectAllowable the allowable drift limit table was deleted. 1610.3.8 drifts for masonry shear wall masonry shear wall buildings. Thus,Story Drift Previously there was no limit on the Allowable buildings. the two sections are equivalent.

allowable drift for single story buildings in Story Driftseismic hazard exposure group I. Newstringent allowable drift limits have beenspecified for masonry buildings.


1994NEHRP

2.3.2 SeismicBase Shear


The statement regarding the amount of 1610.4.1 No Changes Since BOCA did not adopt thesnow load to include in the dead load Seismic Base change to NEHRP, it is moreweight was deleted. Shear restrictive than NEHRP. Thus, the

two sections are equivalent.

Appendix toChapter 2PassiveEnergyDissipationSystems

This section introduces new techniquesfor incorporating energy dissipationdevices into earthquake resistantbUildings. This section is included as anappendix because it is intended to be anintroduction.

No equivalent section Although BOCA does not have anequivalent section, the appendix inNEHRP is just an introduction to thesystems. Therefore, the documentsmay be considered equivalent in thisregard.


1994 NEHRP I Changes 1996 BOCA Changes Comments

No equivalent section 11803.0 Soil This section replaces the Soil Test Since the 1994 NEHRP has noBoring and Procedure. provisions, the 1996 BOCA is moreSampling restrictive. Thus, the sections areProcedure equivalent.

4.2.2 Soil INo Changes I(1805.5 This section, which allowed an Since no change was made to theCapacities Increased increase in loadbearing capacity of 1994 NEHRP Provisions, the 1996

Rock Class 1 and Class 2 rock in certain BOCA is more stringent. Thus, theCapacity) cases, was removed. sections are equivalent.

4.2.2. Soil 1No Changes 11807.1 This section removed the provision Since no change was made to theCapacities Design Loads to increase allowable soil 1994 NEHRP Provisions, the 1996

loadbearing values. BOCA is more stringent. Thus, thesections are equivalent.

4.5.2 Individual spread footings are required to 1810.2 No Changes By not changing this provision, theFoundation have ties only for soft soil, whereas Footing 1996 BOCA is more restrictive thanTies previously ties were required for Seismic Ties the 1994 NEHRP. Thus, the sections

conditions when the soil is anything other are equivalent.than rock.


1994NEHRP


No equivalent section I 1812.0 This section on Foundation Walls Since the 1994 NEHRP has noFoundation was rewritten, incorporating ACI provisions, the 1996 BOCA is moreWalls 530/ASCE 5ITMS 402-95 and ACt restrictive. Thus, the sections are

381-95. Minimum thickness tables equivalent.were added for walls that do notneed to be designed by ACI530/ASCE 5ITMS 402-95 or ACI318-95.

No equivalent section 1815.4Masonry andPlainConcrete

The unsupported height of plainconcrete foundation piers wasreduced. The previous limit was sixtimes the plan dimension. This hasbeen reduced to three times theplan dimension.

Since the 1994 NEHRP has noprovisions, the 1996 BOCA is morerestrictive. Thus, the sections areequivalent.

CHAPTER 5: STEEL STRUCTURE DESIGN REQUIREMENTS


5.1 Reference Seismic Provisions for Structural steel Chapter 35 BOCA references all of the same Since both sections references theDocuments BUildings by AISC was added as a standards that NEHRP does. same standards, the sections are

reference, and as a result, the length of equivalent.this chapter was reduced. Part I isbased on AISC LRFD and Part II isbased on AISC ASD. Updated versionsof LRFD by AISC and StandardSpecification, Load Tables and weightTables for SteelJoists and Joist Girdersare referenced. Another new referenceis Load and Resistance Factor DesignSpecification for Cold-fonned StainlessSteel Structural Members.

5.2 Structural The design of structural steel members 2203.1 No changes Since BOCA already uses ASD andSteel Seismic and connections to resist seismic forces General LRFD, the sections are equivalent.Requirements shall be in accordance with ASD and

LRFD.


1994NEHRP

5.2.1 Requirements forSpecialConcentricallyBracedFrames


This section includes the modifications to 2203.2.1 Three modifications to the AISC Since BOCA does not havethe requirements of Seismic Provisions Modifications Provisions relating to load additional requirements for specialfor structural Steel BUildings. to AISC combinations and columns were concentrically braced frames,

Seismic removed. NEHRP is more stringent. However,Provisions the modifications BOCA removed

were never present in NEHRP.Thus, the two sections are equivalentexcept in the case of specialconcentrically braced frames.

5.3 ColdFormed steelSeismicRequirements

5.7 LightFramed Walls

This section references SeismicProvisions for Structural Steel Buildings(1992), Specification forthe Design ofCold-Fanned steel Structural Members(1986), and Load and Resistance FactorDesign Specification for Cold-FannedSteel Structural Members (1991).Modifications to the references areinduded. The most notable modificationis the use of an earthquake load factor of1.0 instead of 1.5.

Specification for the Design of ColdFonned steel structural Members, Loadand Resistance Factor DesignSpecification for Cold-Fonned SteelStructural Members and Specification forthe Design ofCold-Fonned Stainlesssteel Structural Members arereferenced.

2206.0 I No changesFormed steelConstruction

2204.4.1 Light I No changesFramed Walls

BOCA already has the changesNEHRP has made. Thus, the twosections are equivalent.

BOCA already has the changesNEHRP has made. Thus, the twosections are equivalent.

BOCA

No eqUivalent section (2208.0ReinforcingSteel)

This section, requiring testing ofunidentified reinforcing steel, wasremoved.

-59 -

Since neither document has thisprovision anymore, the two sectionsare equivalent


1994NEHRPTable 1B: Changed Provisions in BOCA and NEHRP JUdged Equivalent

Changes I 1996 BOCA I Changes I Comments

5.6.2 SeismicPerfonnanceCategory C

No changes 2204.3 The additional requirement applying By removing the additionalSeismic to braced frames was removed. requirement, the two sections arePerfonnance equivalent.Category C

No equivalent section 2205.0 OpenWeb steelJoistConstruction

This section was changed to moreclear1y define seismic requirementsand remove testing requirements.


CHAPTER 6: CONCRETE STRUCTURE DESIGN REQUIREMENTS

1994NEHRP Changes 1996 BOCA Changes Comments

6.1 Reference The revised version of ACI 318-89 is Chapter 35 BOCA adopted ACI 318-95 for Since BOCA is using the later versionDocuments used as a reference. The revised Referenced reinforced and plain concrete. of AC1318, it is more upto date than

version includes Building Code Standards NEHRP. Thus, the two sections areRequirements for Structural Plain 1901.0 equivalent.Concrete. Concrete

DesignStandards

6.1.1.4 Requirements for precast elements that 1903.1.1 No Changes BOCA already has this modification,are part of the lateral-force-resisting Modifications but expands it to systems notsystem were added. to AC1318-95 satisfying the requirements of the

chapter, making it more stringent.Thus, the two sections areeqUivalent.

6.1.1.9 No Changes 1903.1.1 This section removed modification Since BOCA is using the later versionModifications to ACI 318 Section 21.3.3.4. ofACI 318, it is more up to date thanto AC1318-95 NEHRP. Thus, the two sections are

equivalent.

6.1.1.13 Provisions for coupling beams were 1903.1.1 No Changes Since BOCA already has thisadded. Modifications modification, the two sections are

to AC1318-95 equivalent.



6.5.1 Ordinary New requirements for ordinary moment 1903.3.1 No Changes Since BOCA already had thisMoment frames with seismic performance Ordinary provision, the two sections areFrames category B were added. Moment equivalent.

Frames inSeismicPerformanceCategory B

6.6.3 Plain New requirements for plain concrete 1904.3.1 This section added exceptions to The changes to both sections nowConcrete footings, walls in the basement, Footings the footing provisions. make them equivalent.

foundation, or other walls below the basewith seismic performance category Cwere added.

6.7.4 Plain A new provision states that structural 1904.4 No changes Since BOCA already had thisConcrete members of plain concrete are not Seismic provision, the two sections are

permitted in bUildings assigned to Performance equivalent.category 0 or E (with some exceptions). Category 0

and E

Appendix to A new appendix was added to introduce No equivalent section Although BOCA does not haveChp.6 provisions for structural systems equivalent provisions, the appendix inReinforced composed of precast concrete elements NEHRP is just an introduction to theConcrete interconnected with dry connections. systems. Therefore, the sectionsStructural may be considered equivalent.SystemsComposedfrom Inter-connectedPrecastElements

No equivalent standard 1906.2 This section added ASTM C595 for Since the 1994 NEHRP has noCements cement conformance. provisions, the 1996 BOCA is more

restrictive. Thus, the sections areequivalent.

BOCA - 61 - NIST Code Comparison

td NEHRP Judaed EBOCAdPTable 1B: Ch - ....1994 NEHRP Changes 1996 BOCA Changes Comments

No equivalent section 1906.5.2 This section reworded the welding Since the 1994 NEHRP has noWelding procedures such that a specification provisions, the 1996 BOCA is more

is required on the construction restrtctive. Thus, the sections aredocuments. equivalent.

No equivalent figure Figure The map was revised. Since the 1994 NEHRP has no1907.1.2 provisions, the 1996 BOCA is moreWeathertng restrtctive. Thus, the sections areProbability equivalent.Map forConcrete

No equivalent section 1907.1.2.1 This section revised the compliance Since the 1994 NEHRP has noCalculation of of maximum water-cementititous provisions, the 1996 BOCA is moreWater- ratio. Table 1907.1.3 was added. restrtctive. Thus, the sections areCementitious equivalent.Matertal

No equivalent section 1907.1.2.2 This section revised the limitations Since the 1994 NEHRP has noLimitations on to those ofACI318-95. provisions, the 1996 BOCA is moreUse of Certain restrtctive. Thus, the sections areCementitious equivalent.Matertals

No equivalent section 1907.1.3 This section revised protection from Since the 1994 NEHRP has noProtection sulfate compliance from AC1318-89 provisions, the 1996 BOCA is morefrom Sulfate to Table 1907.1.3. restrtctive. Thus, the sections are

equivalent.

No equivalent section 1908.2 This section removed modifications Since the 1994 NEHRP has noSelection of toAC1318. provisions, the 1996 BOCA is moreConcrete restrtctive. Thus, the sections areProportions equivalent.

No equivalent section 1909.2 This section was reordered. Since the 1994 NEHRP has noRemoval of Schedules, submittals, and provisions, the 1996 BOCA is moreFonns and unshored construction were added restrtctive. Thus, the sections areShores, and to the section. equivalent.Reshortng


ed Provisions in BOCA and NEHRP JudLlD.US_4.i1_COI&S_4'PXS'I_4S.4SSISU_4S_4


8.1.2 Thirty-fIVe material standard references Chapter 35 Eleven ofthe standards referenced Because BOCA does not referenceReference were added. Referenced in NEHRP were not referenced in all ofthe standards in NEHRP, theDocuments Standards BOCA. However, most of those not two sections are not equivalent.

referenced were testing standards However, material standards are notor material standards not related to that critical in tenns of equivalence.masonry.

No equivalent section I 2104.9.2 Joint This section changed the allowable Since the 1994 NEHRP has noReinforce- defonnation of joint reinforcement provisions, the 1996 BOCA is morement using longitudinal wires. restrictive. Thus, the sections are

equivalent.

8.3.2 No change. Uses ACI 530/ASCE 5/TMS 2101.1.2.1 This section changed from the Since BOCA has limitations on theEmpirical 402-92 in its entirety. Limitations applicability of the Empirical use of Empirical Masonry Design, it isMasonry Masonry Design to limitations of the more stringent. Thus, the twoDesign method. sections are equivalent.

8.3.2 No change. Uses ACI 530/ASCE 5/TMS Table 2106.2 This table decreased one strength Since BOCA is using the moreEmpirical 402-92 in its entirety. Allowable requirement for masonry of hollow current values in ACI 530/ASCEMasonry Compressive loadbearing units. 5/TME 402-95, it is more up to dateDesign Stresses for than NEHRP. Thus, the two sections

Empirical are equivalent.Design ofMasonry

No equivalent section 12108.3 This section added a provision Since the 1994 NEHRP has noMasonry concerning masonry foundation provisions, the 1996 BOCA is moreFoundation walls. restrictive. Thus, the sections areWalls equivalent.

No equivalent section \2111.1.8 This section added a provision Since the 1994 NEHRP has noWeepholes concerning weepholes. provisions, the 1996 BOCA is more




No equivalent section 2112.3 This section added a restriction to Since the 1994 NEHRP has noSupport on glass-block panels supported by provisions, the 1996 BOCA is moreWood wood members to those designed restrictive. Thus, the sections are

for it. equivalent.

8.3.9 Seismic The requirement for solid grouting of 2101.2 BOCA uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 doesPerformance structural masonry that is not part of the Seismic 402-95 in its entirety. have provisions for solid grouting ofCategory E seismic resisting system was removed. Requirements structural masonry that is not part of

8A.8.1 the seismic resisting system. Thus,

Construction BOCA is more restrictive and the two

Requirements sections are equivalent.

8.3.10 The table containing values of the 2101.2 BOCA uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 usesProperties of modulus of elasticity (8.3.10.2) was Seismic 402-95 in its entirety. the table previously used in NEHRP.Materials removed in lieu of calculating the Requirements The table results in lower moduli in

modulus using Eq. 8.3.10.2. The values clay masonry and concrete masonryof modulus of rupture in Table 8.3.10.5.1 with a strength greater than 3000 psi.were revised. Since a lower modulus results in a

lower stiffness, BOCA is morestringent except for concretemasonry with low strengths. Thus,the two sections are equivalent.

8.3.12 Plate, The calculations for the design axial and 2101.2 BOCA uses ACI 530/ASCE 5ITMS A comparison of the equationsHeaded and shear strengths were revised (Eq. Seismic 402-95 in its entirety. indicates that ACI 530/ASCE 5ITMSBent Bar 8.3.12.1-1,8.3.12.1-2,8.3.12.2-1, Requirements 402-95 is more stringent in two oftheAnchor Bolts 8.3.12.2-2). four equations. Thus, neither section

is more stringent, the two sectionsmay be considered eqUivalent.

8.6.3 Design The allowable flexural compressive 2101.2 BOCA uses ACI 530/ASCE 5ITMS ACI530/ASCE 5ITMS 402-95 usesof Plain stress for unrelnforced masonry in non- Seismic 402-95 in its entirety. the previous limit of 0.33fm. Thus,Unreinforced seismic applications is now proportional Requirements BOCA is more restrictive and the twoMasonry to a strain up to 0.85fm. The previous sections are equivalent.Members version limited this condition to 0.33fm.



8.7.2 Shear The 2/3 factor that was applied to shear 2101.2 BOCA uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 usesStrength strength when comparing it to the shear Seismic 402-95 in its entirety. working stress equations to

demand was removed. Requirements determine shear and, thus, a directcomparison is not possible.However, since the intent of strengthdesign is not to provide a morestrigent method but to provide a moreaccurate method of design, the twosections may be consideredequivalent.


Table 1B: Ch dP BOCA and NEHRP Judaed E t1994NEHRP Changes 1996 BOCA Changes Comments

No equivalent sections 2113.0 These sections conceming Since the 1994 NEHRP has noFireplaces masonry chimneys were either provisions, the 1996 BOCA is moreand Chimneys rewritten or added. restrictive. Thus, the sections areFlues equivalent.

2114.0MasonryChimneys,GeneralRequire-ments

2115.0MasonryChimneys forLow-HeatAppliancesandFireplaces.

2116.0MasonryChimneys forMedium-HeatAppliances

2117.0MasonryChimneys forHigh-HeatAppliances


Chanaed Provisions in BOCA and NEHRP Judi.iJ_O_C_GXS_4ELCSiI_CS_C3.

1994NEHRP


9.4.1ConstructionLimitations,ConventionalConstruction

BOCA

Changes

Several reference documents have neweditions and there are a few newreferences.

The limits for conventional constructionfor buildings have been revised. Theheight of the building is no longer acriteria. The required spacing betweenbraced walls has been increased forseismic performance categories A and B.Previously all SPC A buildings could useconventional construction, now there arelimitations. Previously the maximumnumber of stories permitted forconventional construction of SPC Cbuilding was 1 and now it is 2.Previously SPC D buildings could notutilize conventional construction inseismic hazard exposure groups II andIII, and now conventional constructionmay be used for one story buildings witha maximum distance between bracedwalls of 25 ft.

1996 BOCA

Chapter 35ReferencedStandards

Changes

The referenced standards are moreupdated versions of the standardsused by NEHRP.


- 67-

Comments

Since BOCA uses the more updatedversion of standards, it is just as ormore stringent than NEHRP. Thus,the sections are equivalent.

Since there are no conventionalconstruction procedures in BOCA, itis more stringent than NEHRP. Thus,the sections are equivalent.


1994NEHRP

9.9.1.1Structural-UseShear Panels


There are no restrictions in the use of ITable 2305.2 The use of particleboards is more Since there are no restrictions inparticleboards. Fastening restrictive in the 1996 BOCA than in NEHRP on the use of particleboards,

Schedule the 1993 BOCA. Particleboards BOCA is more stringent. Thus, the2305 15 1 cannot be used as subflooring or sections are equivalent.Roof'De~king roof sheathing unless it can beand shown that it meets theSheathing requirements ofwood structural

panels.2306.4.7ParticleboardShear WallSheathing

2308.0Particleboard

BOCA

No equivalent table

No equivalent provisions

No equivalent provision

Table 2305.2FasteningSchedule

2305.6.3GirderSupports

2305.18 FireCuts

2309.4 WallInsulation

2305.14.1Floor Spans

This table removed 1" or greaterWood Structural Panel Roof andWall Sheathing and added severalfootnotes restricting nail spacingbased on basic wind speed.

These documents changed toaccount for concrete walls as wellas masonry walls.

This section added bracingrequirements of floors and roofspans.

- 68-






No equivalent provision 2305.16 BOCA moved and rewrote the Since the 1994 NEHRP has noBridging Bridging section. This section used provisions, the 1996 BOCA is more

to be part of the Flooring section. restrictive. Thus, the sections areequivalent.

No eqUivalent provision 2305.17 This section reduced minimum Since the 1994 NEHRP has noFoundation anchor bolt embedment depth to 7 provisions, the 1996 BOCA is moreAnchorage inches for both concrete and restrictive. Thus, the sections are

masonl)'. eqUivalent.

No eqUivalent provision 2309.4.1 This section added a requirement Since the 1994 NEHRP has noProtection for protection of exterior fiberboard. provisions, the 1996 BOCA is more



ed Provisions in UBC and NEHRP Jud

1994NEHRP

1.2 Scope

1.6.2.1FoundationSpecialInspection

1.6.2.7.1SpecialInspection ofStructuralWood

Changes

This section lists structures that areexceptions to seismic design provisions.Exceptions for one and two familydwellings that were previouslydependent on Av, were revised todepend on a new coefficient Ca.

The requirement for continuous specialinspection for placement of concrete wasadded. The requirement for continuousspecial inspection for construction ofdrilled piles and caissons was changedto periodic inspection. The requirementfor periodic inspection for placement ofreinforcing steel was added.

The requirement for continuous specialinspection during field gluing operationswas defined to be for elements of theseismic force resisting system.

1997 USC

1629.1 Basisfor Design

1701.5 TypesofWork

Changes

No major changes

No changes


Comments

Depending on the soil type, thechange in parameters in NEHRPmay require one and two story woodframe dwellings in seismic zone 1tobe designed to seismic provisions.This is more stringent than UBCwhere all one and two familydwellings in seismic zone 1 need notconform to seismic provisions. Thus,the sections are not equivalent.

Since UBC has exceptions forspecial inspection ofthe placement ofconcrete, the sections are notequivalent. Regarding piles andcaissons, UBC is more stringentsince continuous special inspection isrequired unless the building officialallows periodic inspection. UBC ismore stringent regarding reinforcingsteel since UBC only allows forperiodic special inspection (ratherthan continuous) under certainconditions. Therefore, thedocuments are equivalent withrespect to piles and caissons andreinforcing steel.

Since UBC does not have specialinspection requirements for wood,the sections are not equivalent.

USC ·70· NIST Code Comparison

td NEHRP Judaed Not EuscdPTable 2A: Ch .... -

1994 NEHRP Changes 1997 UBC Changes Comments

1.6.2.7.2 The requirement for periodic special No equivalent provision Since usc does not have specialSpecial inspection for nailing, bolting, anchoring, inspection requirements for wood,Inspection of and other fastening was defined to the sections are not equivalent.Structural pertain to all seismic components.Wood

1.6.2.8 The criteria for requiring special No equivalent provision Since USC does not have specialSpecial inspection changed from the inspection requirements forInspection of performance criteria factor P, which architectural components, theArchitectural depends on seismic hazard exposure sections are not equivalent.Components group and the item to be braced, to the

seismic performance category, whichdepends on Av and seismic hazardexposure group. Exceptions to periodicspecial inspection were added andadditional items requiring inspection wasadded.

1.6.2.9 The criteria for requiring special No equivalent provision Since USC does not have specialSpecial inspection changed from performance inspection requirements forInspection of criteria P to seismic performance mechanical and electricalMechanical category (see above). The items components, the sections are notand Electrical requiring special inspection were revised. equivalent.Components

1.6.3.1.1 The requirement to examine the certified No equivalent provision Since USC does not have provisionsTesting of mill test reports for each shipment of for mill test reports, the sections areReinforcing reinforcing steel was defined to pertain to not equivalent.Steel steel used to resist flexural and axial

forces in reinforced concreteintermediate and special moment framesand boundary members of reinforcedconcrete or reinforced masonry shearwalls.

UBC -71 - NIST Code Comparison

ed Provisions in UBEs:~.i~5.ti~E!d~c~u_~_~ f\Jot Equivalent

1994NEHRP.

2.2.2StructuralFramingSystems

UBC

Changes

New building frame systems, particular1yrelating to composite systems, wereadded. R and Cd values for ordinarymoment frames of reinforced concreteand intermediate moment frames ofreinforced concrete were increased.

1997 UBC

1629.6StructuralSystems

Changes

Three new structural systems wereadded. Structural systemcoefficients were revised, howeverthe approach to calculating baseshear was also revised. Values forR were proportionally scaled downdue to the change to strengthdesign.

·72·

Comments

Because of the new compositesystems added in NEHRP, there aremore structural system categoriesthan UBC. UBC allows for compositesystems in section 1605.2 whichstates that any system may be usedprovided it is based on a rationalanalysis in accordance with wellestablished principles of mechanics.Since UBC does not specifically allowcomposite systems, the sections arenot equivalent. Equivalence betweenthe documents could bedemonstrated. In some cases Rvalues in NEHRP are larger and insome cases they are smaller. Thedocuments are essentially equivalentin their values. NEHRP includes Rvalues for plain concrete andmasonry wall structures that UBCdoes not.


1994 NEHRP

2.2.5.1.2Anchorage ofConcrete orMasonryWalls

Table 2A: Changed Provisions in USC and NEHRP Judged Not EquivalentChanges I 1997 USC I Changes I Comments

Although there were no changes in this 1633.2.8.1 This new section includes NEHRP presents 2 formulas forsection, the formula to calculate the Out of Plane provisions for anchoring walls to calculating design forces. The firstanchorage force in section 3.1.3 was Wall flexible diaphragms. The formula is similar to and will producerevised. Anchorage to requirements for connections to similar values as rigid diaphragms in

Flexible flexible diaphragms are more USC. The second formula inDiaphragms stringent than connections to rigid NEHRP depends on the system

diaphragms. Using the formula that ductility. For flexible diaphragms independs on system ductility (Eq. USC the amplification factor is32-2), the design load is 50% larger increased by 50%, whereas infor flexible diaphragms. The NEHRP, it is doubled in the centerminimum design load is 420 Iblft half of the span. This puts NEHRPwhich 50% larger than the minimum loads 33% higher in the center half offor rigid diaphragms. the diaphragm span. The minimum

design value in NEHRP depends onCa which will give a maximum valueof 4401blft; this is 20 Iblft greater thanthe minimum value required in USC.Using the first formula for calculatingthe load, the documents will beequivalent. Using the secondformula for calculating the load,NEHRP values are more stringentand the documents are notequivalent. Near field effects inseismic zone 4 will increase the loadsin USC.

USC -73 - NIST Code Comparison

1994NEHRP


2.2.7Deflection andDrift Limits

The category for single story buildings in 1630.10 Story Due to the change in design forces,the allowable drift limit table was deleted. Drift the maximum allowable story driftPreviously there was no limit on the Limitations was revised. The limit is 0.025allowable drift for single story bUildings in times the story height for structuresseismic hazard exposure group I. New with a period less than 0.7 secondsstringent allowable drift limits have been and 0.020 times the story height forspecified for masonry buildings. structures with a period greater than

0.7 seconds.

The NEHRP drift limits are morestringent. NEHRP has strict driftlimits that apply to masonry buildingswhich UBC does not. Drift is usuallyonly a concern for frame buildings, inwhich case the sections are notequivalent. Drift is a measure ofdamage and not a life safety issue.In that respect, the documents areequivalent from a performancestandpoint.


USC

The statement regarding the amount ofsnow load to include in the dead loadweight was deleted.

1630.2.1Design BaseShear

1630.2.3SimplifiedDesign BaseShear

The method for calculating baseshear was completely revised. Thedesign level was changed fromallowable stress to strength based.New soil categories, near fieldeffect, and seismic source type areadditional parameters used incalculating the base shear. Aformula for a new simplified designbase shear was added whichproduces loads larger than thestatic force procedure. Theadvantage of using the simplifiedbase shear procedure is lesscalculation effort.

-74 -

One of the main differences in thebase shear calculation is that UBCincludes near field and importancefactors. These factors will onlyincrease the base shear. The otherdifference is the dependence on theperiod. The base shear in UBC isproportional to 1rr whereas it isproportional to 1rr213 in NEHRP. Forstructures with a period greaterthan1, with no concern for near field andimportance, NEHRP loads will belarger. Thus, for long periodstandard occupancy structures thatare not in the near field, the sectionsare not equivalent. For all otherconditions, the sections areequivalent. Since the simplified staticprocedure in UBC is conservative,the sections are equivalent.


1994 NEHRP


Table 2A: Changed Provisions in USC and NEHRP Judged Not EquivalentChanges I 1997 UBC I Changes I Comments

In calculating Cs, the seismic response 1630.2.1 ISee above for discussion on base ISee above for discussion on basecoefficient, Cv replaces AvS and Ca Design Base shear shearreplaces Aa in the equations. Using Shearthese new coefficients, the base shear islowered for structures on rock but isincreased for structures on soft soils.The base shear of a structure is V=CsW.

CHAPTER 3: ARCHITECTURAL, MECHANICAL AND ELECTRICAL COMPONENTS DESIGN REQUIREMENTS

1994NEHRP

3.1.3 SeismicForces

UBC

Changes

Previously, lateral force calculations forarchitectural and mechanical/electricalequipment were separated. In the newprovisions, general formulas for allequipment are provided. The formulasdepend on Ca, importance factor of theequipment, component amplification,response factors, and vertical location ofthe equipment in the building.

1997 UBC

1632.2Design forTotal LateralForce

Changes

New formulas for calculating thelateral force on nonstructuralcomponents are introduced. Theforce may be calculated with asimple formula that gives an upperbound to the load or by taking intoaccount the type of equipment andvertical location of the equipment inthe building. Response coefficientsare included for different types ofequipment.

·75·

Comments

The documents provide similarformulas for calculating the lateralforce on nonstructural components.UBC includes near field effects inseismic zone 4 that may result in ahigher load. The componentcoefficients vary in the two codes; insome instances NEHRP is higherand it is sometimes lower. Bothdocuments have a penalty for nonductile component anchorage. Theimportance factor in NEHRP is morecomponent dependent than in UBC.With all factors considered, thesections are essentially equivalent.Parapet design loads are anexception. The response coefficientis smaller and the importance factoris larger in NEHRP. Therefore, withrespect to parapets, NEHRP willproduce larger loads and thesections are not equivalent.


td NEHRP Judaed Not EuscdPTable 2A: Ch -- .... -

1994 NEHRP Changes 1997 USC Changes Comments

3.1.5 New importance factors are introduced Table 16-K No changes The importance factor forComponent which depend on the severity of failure of Occupancy components that contain hazardousImportance the component. Category and essential substances areFactor equivalent in the documents.

NEHRP places a greater importanceon components that may be a fallingor egress hazard. Thus, in thisrespect, the documents are notequivalent.

3.2.6 This new section outlines additional Table 16-0 No changes relating to suspended NEHRP contains more detailedSuspended requirements for bracing suspended Horizontal ceilings requirements for suspended ceilingsCeilings ceilings. Force Factors than USC. Thus, the sections are

Design and construction references and not equivalent. They may be provenminimum dearances are among the equivalent if NEHRP requirements

additional requirements. are met.

3.2.7 Access This new section outlines additional Table 16-0 A new footnote states that only NEHRP contains more detailedFloors requirements for bracing access floors. Horizontal anchorage or restraints need be requirements for access floors than

The weight used to calculate loads and Force Factors designed. USC. Thus, the sections are notthe requirements for special access equivalent. They may be provenfloors are induded. equivalent if NEHRP requirements

are met.


1994 NEHRP

3.2.9 steelStorageRacks


This new section outlines additional Chp. 22 Div. X Consistent with changes to base Both documents adopt the samerequirements for bracing steel storage Design shear, the calculation of earthquake reference design standard. NEHRPracks. The weight used to calculate loads Standard for loads was revised. requires the seismic weight to be theand the response factor to design Steel Storage weight of the storage rack plus 67%storage racks is included. Racks of the rated load. UBC requires the

seismic weight to be the weight of therack plus the contents. UBC allowsfor a 50% reduction in the weight ofthe contents ifthere are a minimumof four columns in any direction oneach column line designed to resisthorizontal forces. Thus, when UBCallows for reduction, the sections arenot equivalent.


Extensive requirements for bracingvarious mechanical and electricalcomponents such as piping, elevators,and storage tanks are provided.

Table 16-0HorizontalForce Factors

Varioussections

The majority of the bracingrequirements is in footnotes ofTable 16-0.

NEHRP contains more detailedrequirements for the variousmechanical and electricalcomponents. Thus, the sections arenot equivalent. They may be provenequivalent if NEHRP requirementsare met.


1994NEHRP

4.5.2FoundationTies

USC

Changes

Individual spread footings are required tohave ties only for soft soil, whereaspreviously ties were required forconditions when the soil is anything otherthan rock.

1997 USC Changes


-77 -

Comments

Since UBC does not require ties forspread footings, the sections are notequivalent.


Chana?~J~L~Y::,~e!1~1~es~~_f§:_r2_4~EHRP Jud

1994 NEHRP Changes 1997 UBC Changes

6.1.1.8 This section includes provisions for No equivalent provisioncalculating the probable capacities ofstructural elements in precast concreteframes.

6.2.2 strength A provision was added that states that 1923.2 I No changesof Anchors anchors shall be detailed so that the Strength

connection failure is initiated by the Designfailure ofthe anchor steel rather than bythe failure of the surrounding concrete.

6.5.2 Moment A new provision was added that states 1921.8 I No changesFrames that moment frames on soil profile type E Requirements

or F with seismic performance category for Frames inS shall be an intermediate moment Seismic Zoneframe. 2

Comments

Since no equivalent provisions existin USC, the sections are notequivalent.

Since USC does not require aparticular failure sequence, thesections are not equivalent.

USC states that frames in seismiczone 2 are required to beintermediate moment frames.Without concern to soil type, NEHRPis more stringent since seismicperformance category S tends to bein a lower seismic zone than zone 2.Thus, the sections are not equivalent.

6.6.3 PlainConcrete

UBC

New requirements for plain concretefootings, walls in the basement,foundation, or other walls below the basewith seismic performance category Cwere added.

1922.6 Walls

1922.7Footings

New requirements for structuralplain concrete walls and footingswere added.

-78 -

The requirements in NEHRP andUSC do not tend to address thesame issues. Requirements inNEHRP relate to minimumreinforcements and requirements inUSC are related to design loads.Since NEHRP has requirements thatare not in USC, the sections are notequivalent.


ed Provisions in UBC and NEHRP Judi_4.i!i.O_4SESS&SSSC.ai_US_USS_C£SS&S_tl&SLI_CS.tS.

1994NEHRP Changes 1997 UBC Changes Comments

Chapter 7 This new chapter presents design and 1605.2 No changes USC does not have a chapterComposite detailing requirements for composite Rationality dedicated to composite construction.Steel and structures that are expected to provide USC allows for composite systems inConcrete structural toughness, ductility, strength, section 1605.2 which states that anyStructure and stiffness eqUivalent to comparable system may be used provided it isDesign concrete and steel structures. based on a rational analysis inRequirements accordance with well-established

principles of mechanics. Since USCdoes not specifically allow compositesystems, the sections are notequivalent. However, equivalencecould be demonstrated.

7.4 Requirements to design composite 1605.2 No changes See above for discussion onComposite systems (partially restrained frames, Rationality composite systems.Systems ordinary moment frames, special

moment frames, concentrically bracedframes, eccentrically braced frames,reinforced concrete walls composite withsteel elements and composite shearwalls) are in this section. The sectionoutlines the design requirements forindividual elements ofthe system.

7.5.1 The requirements for designing Chapter 19 See specific material sections for Although NEHRP referencesComposite composite slabs are included in this Concrete any changes sections common to USC, it providesSlabs section. Chapter 22 additional requirements. Thus, the

Steel sections are not equivalent.

UBC -79· NiST Code Comparison

1994NEHRP

7.5.2CompositeBeams

7.5.3 EncasedCompositeColumns


Additional requirements for special Chapter 22 See steel section for any changes The documents are equivalent inmoment frames are given as follows. A Steel composite beam designmaximum distance from the maximum requirements since they bothconcrete compression fiber to the plastic reference LRFD. Since NEHRP isneutral axis is given. Compression less stringent in the width-thicknesselements that are fully encased by a requirement, the documents arereinforced concrete cover (min 2'~ do not equivalent in this respect. Sinceneed to meet the width-thickness ratio NEHRP has an extra requirement forprovided that concrete is confined by the maximum distance to the plastichoop reinforcement in regions where neutral axis, the documents are notplastic hinges are expected to occur. equivalent in this respect.

This section references LRFD for the Chapter 19 See specific material sections for NEHRP requires additional concretedesign of encased composite columns. Concrete any changes detailing that is similar toAdditional requirements for seismic Chapter 22 requirements in the ACI. Since UBCperformance category C, 0 and E are Steel references LRFD and ACI thegiven. Most of the additional referenced provisions are the samerequirements are related to concrete but the concrete detailing would notreinforcing. be used in conjunction with steel as

NEHRP requires it. Thus, thesections are not equivalent.

7.5.4 FilledCompositeColumns

USC

This section outlines the requirements forfilled composite columns. LRFD isreferenced and additional requirementsare given for seismic performancecategories 0 and E.

Chapter 19Concrete

Chapter 22Steel

See specific material sections forany changes

- 80-

NEHRP has additional requirementsfor composite columns that usessections from various references.Although USC references the samedocuments, the provisions are notrequired in conjunction with eachother. Thus, the sections are notequivalent.


1994 NEHRP

7.6CompositeConnections


This section includes requirements for Chapter 19 See specific matelial sections for UBC does not have a sectionconnections in structures with composite Concrete any changes dedicated to composite connections.or dual steel-concrete systems where Chapter 22 Much of the requirements in NEHRPseismic loads are transferred. Steel reference documents that UBC

references. Since there areadditional requirements, the sectionsare not equivalent.

CHAPTER 8: MASONRY STRUCTURE DESIGN REQUIREMENTS

1994NEHRP


8.3.8 SeismicPerformanceCategory 0


Changes

The screen wall requirements wereremoved. Requirements for wallsseparated from the basic structuralsystem were added. The restliction onuse of structural clay nonload-bealingwall tile (ASTM CS6) was removed.

The required roughened surfaceexposure for concrete placement next tomasonry that is not designed with aseparation joint was increased from1/16" to 1/8".

Bundling of bars is no longer allowed.

1997 USC

2106.1.12.3SpecialProvisions forSeismic Zone2

2106.1.12.4SpecialProvisions forSeismicZones 3 and 4

ValiousSections

Changes

No changes

The exception to having to usespecial provisions for seismic zones3 and 4 changed from a particulartype of building with Group MOccupancies (retail) to Group UOccupancies (plivate garages,carports, sheds, etc.).

No changes

Comments

Since UBC does not haverequirements for walls separatedfrom the basic structural system, thesections are not equivalent.

Since UBC requires a roughenedsurface exposure of 1/16", NEHRP ismore restlictive. Thus, in this regard,the documents are not equivalent.NEHRP does not have anyexceptions to additional requirementsfor seismic performance category 0whereas UBC allows for exceptionsto be made for certain structures inseismic zones 3 and 4. Thus, thesections are not eqUivalent.

Although UBC does not specificallyaddress bundling of bars, it doesstate that no more than 2 bars maybe located in a cell of a wall or a wallframe. Since it appears that NEHRPis more stlingent, the sections are notequivalent.

USC - 81 - NIST Code Comparison

1994NEHRP


Table 2A: Changed Provisions in USC and NEHRP Judged Not EquivalentChanges I 1997 UBC I Changes I Comments

The calculation of embedment length 2108.2.2.6 No changes With the change to the formula in(Eq. 8.4.5.2) was modified. A Development NEHRP, the embedment lengthrequirement for 6 inches of minimum 2108 2 6 2 4 formulas are equivalent. USC doesembedment length for wire was added. Reinio~c~- . not specify a minimum embedmentThe calculation of embedment length for ment for wire; the minimum embedment forhooks (Eq. 8.4.5.4.2) was modified. Lap all bars is 12 inches. Thus, USC issplices are no longer allowed in plastic more stringent and the sections arehinge zones. equivalent. In USC, the required

extension of a hook depends on theangle ofthe bend. The lengthrequired in NEHRP is almost equal tothat in USC when there is a 90degree bend on the hook. For largerbends, USC allows less extension,therefore the sections are notequivalent. Since USC requires thecenter of a lap splice to be at thecenter of the member clear length(outside ofthe plastic hinge zone),the sections are equivalent.

8.5.4DeformationRequirements

UBC

This section was rewrttten to beconsistent with the deformation criteriaset forth in Chapter 2.

2108.2.4.6DeflectionDesign

2108.2.3.2DesignAssumptions

2108.2.6.2.7Pier DesignForces

There were no changes to thedeflection limitations. The formulafor calculating the effective momentof inertia was deleted. The codestates that effects of cracking onmember stiffness shall beconsidered. A formula to calculatethe midhelght deflection of a wall isgiven that incorporates the serviceand cracked moments.

·82·

The deflection limitations areequivalent. NEHRP gives a formulafor calculating the effective stiffnesswhereas USC does not. Thus, thesections are not equivalent.


td NEHRP Judaed Not EuscdPTable 2A: Ch- ...1994 NEHRP Changes 1997 USC Changes Comments

8.7.3 Design The equations to calculate shear 2108.2.3.6.2 No changes Outside the plastic hinge zones, andof Reinforced strength in both the masonry and Nominal without the effect of tension loads,Masonry reinforcing steel were modified (Eq. Shear the formula in NEHRP will give largerMembers 8.7.3.2-1,8.7.3.3). Strength shear capacities for masonry. Thus,

the documents are not equivalent forthis condition. The shear capacity ofmasonry in NEHRP is increased withcompressive axial load anddecreased with tension. In the plastichinge zone, depending on the axialload, USC capacities may be higher.Since the shear capacity ofreinforcement is larger in USC, thesections are equivalent.

USC - 83- NIST Code Comparison

Chanaed Provisions in USC and NEHRP Jud.c_csS_C_CS.SLO_'_C&S.CCLCSCI_CY_CSSL.".CS_'

1994NEHRP


USC

Changes

The limits for conventional constructionfor buildings have been revised. Theheight of the building is no longer acriteria. The required spacing betweenbraced walls has been increased forseismic performance categories A and S.Previously all SPC A buildings could useconventional construction, now there arelimitations. Previously the maximumnumber of stories permitted forconventional construction of SPC Cbuilding was 1 and now it is 2.Previously SPC D buildings could notutilize conventional construction inseismic hazard exposure groups II andIII, and now conventional constructionmay be used for one story buildings witha maximum distance between bracedwalls of 25ft.

1997 USC

2320.1General

2320.4.1SracedWallsLines

2320.5.1SracedWallLines

Changes

No changes. USC allows thefollowing structures to beconstructed of conventional lightframe: 1) 1-3 story residences 2) 1story standard occupancystructures constructed on slab-ongrade 3) private garages, carports,sheds, agricultural buildings, fencesover 6' high, tanks and towers 4)top story walls and roof of standardoccupancy structures not exceeding2 stories of wood framing 5) interiornonload-bearing partitions, ceilingsand curtain walls in all occupancies.USC requires braced walls inseismic zones 0-3 to be spaced at34' and 25' in seismic zone 4.

- 84-

Comments

The requirement for braced walls ismore stringent in NEHRP. USCrequires a spacing of 25' in seismiczone 4 whereas NEHRP requires it inseismic performance categories Cand D. Therefore, regarding bracedwalls, the documents are notequivalent. NEHRP bases limits ofconventional construction on seismicperformance category and number ofstories. USC bases it on type ofoccupancy and does not limit thestories of a building based on aspecific zone. With regard toresidences, NEHRP is more stringentsince USC allows all 1-3 storyresidences to be constructed ofconventional construction, whereasthe number of stories in NEHRP islimited by the seismic performancecategory. Therefore with regard toresidences, the documents are notequivalent. With regard to standardoccupancy structures, USC is morestringent since the structure is limitedto a single story whereas in NEHRP,depending on the seismicperformance category, a highernumber of stories may be allowed.Therefore, with regard to standardoccupancy structures, the documentsare not equivalent.


Table 2A: Ch dP UBC d NEHRP Judaed Not E t.1994 NEHRP Changes 1997 UBC Changes Comments

9.9.1.2 Shear Previously, light framed walls sheathed 2315 Wood No changes USC allows for the use of wood,Panels with lath and plaster, gypsum sheathing Shear Walls particleboard and fiberboardSheathed with boards, gypsum wallboard, or fiberboard and sheathing to resist earthquake loadsOther Sheet sheets could be used to resist Diaphragms whereas NEHRP only allows forMaterials earthquake forces. Except in wood panels. Thus, the sections are

conventional construction, new not equivalent.provisions do not allow sheet materialsother than structural-use materials to bepart of the seismic force resisting system.

No eqUivalent provision 2316.2 The form factor for lumber I beams NEHRP does not have any additionalAmendments and box beams were revised. The requirements for form factor beyond

new equation makes the form factor what is in the NOS. Since the form23% larger. factor is directly related to the flexural

capacity, in USC, the capacity will belarger for lumber I beams and boxbeams. Thus, the sections are notequivalent.

UBC ·85· NIST Code Comparison

Table 2B: Changed Provisions in UBC and NEHRP Judged EquivalentCHAPTER 1: GENERAL PROVISIONS

1994 NEHRP Changes 1997 UBC Changes Comments

1.4.2 Seismic Six new soil profile types are defined in 1629.3 Site Six new soil profile types are The soil classifications andCoefficients this section where previously there were Geology and defined in this section where procedures for determining the profile

4. Seismic coefficients Ca and Cv, which Soil Charac- preViously there were 4. Seismic are equivalent in the documents.depend on soil profile and seismic zone, teristics coefficients Ca and Cv, which With near field effects in seismicare introduced in this section. Ca and Cv 1629.4 Site depend on soil profile, seismic zone 4 (Aa,V=O.4), the seismicreplace AaS and Av in the 1991 Seismic zone, distance to seismic source coefficients are larger in USC. In allprovisions. All provisions that were Hazard and seismic source type, are other seismic zones (Aa,v<O.4), andpreviously related to Av and Aa were Characteris- introduced in this section. Distance without near field effects in seismicrevised to reflect the new coefficients. tics to seismic source and seismic zone 4, the coefficients are

1636 Sitesource type were not previously equivalent. Thus, the sections areconsidered. A new section, 1636, equivalent.

Categorization describes the procedure forProcedure determining soil profile type.

1.4.4 Seismic The seismic performance category for Table 16-K No changes The seismic hazard exposure groupPerformance seismic hazard exposure group III Occupancy in NEHRP integrates seismic zoneCategory buildings with values of Av ranging from Category and importance of a structure. This

0.10 to 0.15g was increased from Cto D is used to categorize buildings forto reduce the risk of collapse in essential such things as detailingservice buildings in regions of moderate requirements, similar to the use ofseismicity. seismic zones in USC. Unlike USC,

NEHRP does not base force levelson the importance of a building.Equivalence of the sections must bemade on a case by case basis.

1.6 Quality Quality assurance provisions now apply 1701 Special No changes USC requires inspection of allAssurance to other designated seismic systems in Inspections construction orwork for which a

seismic performance category D. permit is required. Since USCrequires special inspection for allseismic zones, it is more stringent.Thus, the sections are equivalent.

UBC - 86· NIST Code Comparison

1994 NEHRP

Table 2B: Changed Provisions in UBC and NEHRP Judged EquivalentChanges I 1997 USC I Changes I Comments

1.6.1 QualityAssurancePlan

No Changes 1702 An additional condition that requires NEHRP states that the personStructural structural observation of a building responsible for the design of aObservation was added. The additional designated seismic system shall be

condition is for a structure in responsible for the portion of theseismic zone 4, with Na greater quality assurance plan applicable tothan 1, and with a lateral design that system. Since NEHRP does notrequired forthe entire structure. explicitly require structuralStructural observation is performed observation by an engineer orby the architect or engineer architect, USC is more stringent.responsible for the design and is Thus, the sections are equivalent.not in lieu of special inspection.

1.6.2.2.1Special Inspection forReinforcingSteel

1.6.2.2.2Special Inspection forReinforcingSteel

The requirement for petiodic special 11701.5 Typesinspection duting and upon completion of ofWorkreinforcing steel placement inintermediate concrete moment framesand concrete shear walls was added.The requirement for petiodic specialinspection of the placement of steel inreinforced masonry shear walls andordinary moment frames was deleted.

The requirement for continuous special 11701.5 Typesinspection duting the welding of ofWorkreinforcing steel was defined to pertain tosteel resisting flexural and axial forces inintermediate and special moment framesof concrete, and in boundary members ofconcrete shear walls.

No changes

No changes

Since USC requires specialinspection for placement of allreinforcing steel, USC is moresttingent. ThUS, the sections areequivalent.

With exception to the bar type anduse, USC requires special inspectionfor the welding of all reinforcing steel.Since USC is more sttingent, thesections are equivalent.


Table 2B: Ch dP UBC d NEHRP Judaed E t1994NEHRP Changes 1997 USC Changes Comments

1.6.2.3 The requirement for special inspection 1701.5 Types No changes With exception to certain foundations,Special during and on completion ofthe ofWork USC requires special inspection forInspection of placement of concrete for intennediate the placement of all concrete. USCConcrete and special moment frames and requires, without exception,

boundary members of concrete shear continuous special inspection for thewalls was added. The requirement for placement of concrete in specialperiodic special inspection during moment frames. Since UBC is moreplacement of concrete in reinforced stringent, the sections are equivalent.concrete frames and shear walls wasdeleted.

1.6.2.4 The requirement for special inspection 1701.5 Types No changes Similar to NEHRP, UBC requiresSpecial after the completion of placement of ofWork special inspection during and afterInspection of prestressing steel was added. completion ofthe placement of allPrestressed prestressing steel. Thus, theConcrete sections are equivalent.

1.6.2.6.1 An exception to continuous special 1701.5 Types No changes UBC does not make exceptions toSpecial inspection in lieu of periodic inspection ofWork continuous special inspection basedInspection of for welds loaded to less than 50 percent on the stress level of the weld. SinceStructural of their design strength was added. UBC is more stringent, the sectionsSteel Welding are equivalent.

1.6.2.6.2 Bolts in connections identified as not 1701.5 Types No Changes UBC requires the inspection of allSpecial being slip-critical or subject to direct ofWork high-strength A325 and A490 bolts.Inspection of tension need not be inspected for bolt Since UBC is more stringent, theStructural tension other than to ensure that the sections are equivalent.Steel Bolts plies of the connected elements have


1.6.3.1 The requirement for a sample at 1903.1 Tests No changes Since the requirements were deletedTesting of fabricator's plant and the testing of of Materials in NEHRP, the sections areReinforcing reinforcing steel used in certain equivalent.Steel applications was deleted.


td NEHRP Judaed EUBCdPTable 2B: Ch ....1994NEHRP Changes 1997 UBC Changes Comments

1.6.3.1.2 Where ASTM A615 reinforcing steel is 1921.2.5.2 This section has not been changed Since the reference that NEHRPTesting of used to resist earthquake-induced SilletSteel but has been renumbered from uses is directly incorporated in USC,Reinforcing flexural and axial forces in special A615 1921.2.5.1. the sections are equivalent.Steel moment frames and in wall boundary Reinforce-

elements of shear walls in buildings of mentseismic performance category D and E,verify that the requirements of Sec.21.2.5.1 of Ref. 6-1 have been satisfied.

1.6.3.1.3 Where ASTM A615 reinforcing steel is to 1903.5.2 No major changes Since the reference that NEHRPTesting of be welded, verify that chemical tests uses is directly incorporated in USC,Reinforcing have been performed to determine the sections are equivalent.Steel weldability in accordance with Sec. 3.5.2

of Ref. 6-1.

1.6.3.4.3 ASTM A435 and ASTM A898 are added 1703 Non- No changes With changes to NEHRP, theTesting of criteria on which to judge the destructive sections are equivalent.Structural acceptability of base metal thicker than TestingSteel 1.5 in. that is subject to through-

thickness weld shrinkage strains.

UBC - 89- NIST Code Comparison

ad Provisions in ~,~f_,~2~.s~;tt~!st.~~a:d E

1994 NEHRP

2.2.4 AnalysisProcedures

2.2.5.2.7Diaphragms

UBC

No changes

No changes

Changes 1997 UBC

1629.8Selection ofLateral-ForceProcedure

1631.6 TimeHistoryAnalysis

1631.2.9Diaphragms

Changes

A simplified static procedure wasadded which may be used for thefollowing structures of occupancycategories 4 and 5: 1) Buildings ofany occupancy not more than 3stories in height that use light-frameconstruction. 2) Other buildings notmore than 2 stories in height.Previously these buildings wouldutilize the static procedure. Therequirements for time historyanalyses were expanded to indudethe amount and type oftimehistories that are required.Provisions for non-linear timehistory analysis were added.

A new provision limits the length-towidth ratio of a wood subdiaphragmto 21/2: 1.

·90·

Comments

Since NEHRP does not have asimplified static procedure, thebuildings that fall under the simplifiedstatic procedure of UBC wouldrequire a static procedure in NEHRP.As will be addressed, the base shearthat results from the simplified staticprocedure in UBC is larger than thestatic procedure. Although UBCincorporated a simplified procedure,the loads are more stringent,therefore the sections are equivalent.Since NEHRP does not address timehistory analysis, UBC is morestringent in requiring it. Therefore,the sections are equivalent.

Since NEHRP does not haveprovisions for limiting the size ofwood subdiaphragms, the sectionsare equivalent.


1994 NEHRP

2.2.6Combinationof LoadEffects

Table 2B: Changed Provisions in UBC and NEHRP Judged EquivalentChanges I 1997 UBC I Changes I Comments

Load combinations are referenced to 1612 The seismic loads in the previous With the change in UBC, bothANSI/ASCE 7-93 which differ from the Combinations code were at allowable stress levels provisions are strength based andpreviously given combinations. In of Loads and the recommended load the load combinations are equivalent.earthquake load combinations, the dead 1630.1.1 combinations were based on the The horizontal NEHRP earthquakeload factor is slightly higher but the live Earthquake combinations of the material used in loads does not have a factor similarand snow load factors are typically lower. Loads design. The seismic loads in the to the redundancy factor in UBC.The vertical earthquake loads depend on new code are at an ultimate The UBC vertical earthquake forceCa where they previously depended on strength level. The new code has the potential to be larger thanAv. The new vertical loads will be less provides load combinations but also NEHRP because UBC includes anfor soil profile A, equivalent for soil type B refers the user to specific materials importance factor and depending onand in most cases they will be larger for chapters. Load combinations to near field effects, Ca values in UBCsoil types C, D and E. reduce the earthquake loads to could be larger in seismic zone 4.

allowable stress levels are also Since UBC earthquake loadprovided. The new code includes combinations could lead to a largervertical earthquake loads which are force, the sections are equivalent.a function ofthe dead load, Ca, andan importance factor. Areliability/redundancy factor isintroduced which increaseshorizontal earthquake loads for non-redundant structures.

2.3.7.1 StoryDriftDetermination

UBC

No changes 1630.9 Drift The new code requires calculationof a maximum inelastic responsedisplacement from the static designlevel response displacement usingthe ductility factor of the system. Allprovisions in the code that relate todrift were revised to reflect thischange.

·91 •

Both documents amplify deflectionsfrom design level deflections.NEHRP uses a deflectionamplification factor and UBC uses aductility factor. In some cases theamplification for NEHRP is largerthan UBC and in some cases it issmaller. The documents may beconsidered to be essentiallyequivalent in calculating the drift butthe drift limits must also beconsidered in the comparison (see2.2.7).


1994NEHRPTable 2B: Changed Provisions in UBC and NEHRP Judged Equivalent

Changes I 1997 UBC I Changes I Comments

2.4.8 DesignValues

No changes 1631.5.4 New provisions allow for dynamic NEHRP allows a reduction oftheReduction of forces of a regular structure to be modal base shear to the equivalentElastic reduced to 80 percent of the static lateral force procedure base shearResponse base shear if a site specific but does not allow a reduction belowParameter for response spectrum is used. than. Although USC allows a greaterDesign reduction, based on performance, the

sections are judged to be equivalent.This is judged to be the casebecause with a site specificspectrum, it is assumed thatinformation about the site is known togreater detail.

2.6Provisions forSeismicallyIsolatedStructures

2.6.2.3SeismicHazardExposureGroup

UBC

This is a new section based on the 1994USC Appendix Chapter 16, division III.The provisions have been modified toconform to the strength based designapproach and nomenclature ofthedocument.

All portions of the building shall beassigned a Seismic Hazard ExposureGroup

AppendixChp. 16Division IV,EarthquakeRegulationsfor SeismicIsolatedStructures

1657.3OccupancyCategories

Changes were made to this sectionto switch form allowable stress tostrength based design. Changes inthat respect will not be documented.See the following subsections forother major changes.

No changes

·92·

Since NEHRP was based on anear1ier version of USC, it is assumedthat the new USC is equivalent if notbetter than the old version.Therefore, the sections areequivalent

Similar to other provisions, theseismic hazard exposure group inNEHRP integrates seismic zone andimportance of a structure. This isused to categorized buildings forsuch things as detailingrequirements, similar to the use ofseismic zones in USC. Unlike USC,NEHRP does not base force levelson the importance of a bUilding.Equivalence of the sections must bemade on a case by case basis.


1994 NEHRP

2.6.2.5.2EquivalentLateral ForceProcedure


The provisions for using the equivalent 1657.5.2 To use the static lateral procedure, NEHRP allows the static procedurelateral force procedure are included in Static the distance to an active fault that a to be used if the structure is locatedthis section. Analysis structure is required to be located at least 15km from an active fault.

away from was revised from 15km NEHRP is more stringent in thisto 10km. Therefore, the structures requirement since any structurethat are located between 10 and closer than 15km to an active fault15km that previously had to utilize a must be designed by a dynamicdynamic analysis can now use a analysis whereas in USC it is 10km.static analysis. Although NEHRP is more stringent in

requiring a dynamic analysis, sincethe base shear will be scaled, thesections are equivalent.

2.6.2.5.3.3Site SpecificDesignSpectra

2.6.6.2.8InspectionandReplacement

2.6.9.3Determinationof ForceDeflectionCharacteristics

The criteria that would require a sitespecific design spectra analysis isincluded in this section.

Access for inspection and replacementof the isolation system shall be provided.

This section includes a formula tocalculate the effective stiffness of anisolation system.

1657.5.3DynamicAnalysis

1661.2.8InspectionandReplacement

1665.3Determinationof ForceDeflectionCharacteristics

To require a site specific designspectra, the maximum distance thata structure may be located from anactive fault was revised from 15kmto 10km. The provision that statesthat structures located in seismiczones 1, 2A or 2B and structureswith an isolated period of 3 secondsor more require a site specificspectrum was deleted.

Additional requirements forinspection were added.

An additional formula to calculatethe effective damping of an isolatorunit is included.

NEHRP is more stringent since thereare provisions that state that a sitespecific design spectra is required ifthe structure is located within 15kmof an active fault or if the isolatedperiod ofthe building is greater than3 seconds. Although NEHRP ismore stringent in requiring a dynamicanalysis, since the base shear will bescaled, the sections are equivalent.

Since NEHRP is equivalent to the1994 USC, it does not have theadditional requirements set forth inthe 1997 USC. Therefore, the 1997USC is more stringent, and thesections are equivalent.

The formula to calculate effectivestiffness is equivalent in thedocuments. NEHRP does notinclude a formula to calculateeffective damping. Thus, thesections are essentially equivalent.


Table 2B: Ch dP UBC d NEHRP Judaed E t1994NEHRP Changes 1997 USC Changes Comments

2.6.9.4 This section includes the criteria to judge 1665.4 No major changes USC requires the specimen to have aSystem adequacy in test specimens. Systems positive incremental force-canyingAdequacy Adequacy capacity whereas NEHRP does not.

USC requires no greater than 10percent difference in stiffnesswhereas NEHRP allows up to 15percent difference. Therefore, USCis more stringent and the sections areequivalent.

2.7 Provisions This new section includes requirements 1634 Consistent with other changes, this The two sections are equivalent infor to design all self-supporting structures, Nonbuilding section was revised to incorporate intent. It is apparent that the sectionNonbuilding other than buildings, bridges and dams, Structures the change from allowable stress in NEHRP was modeled after USC.Structures that are supported by the earth, that design to ultimate strength design. Therefore, the sections are

cany gravity loads, and that may be equivalent.required to resist the effects of anearthquake.

Appendix to This section introduces new techniques No equivalent section Although USC does not have anChapter 2 for incorporating energy dissipation equivalent section, the appendix inPassive devices into earthquake resistant NEHRP is just an introduction to theEnergy buildings. This section is included as an systems. Therefore, the sectionsDissipation appendix because it is intended to be may be considered equivalent.Systems introduction.


Chanaed Provisions in UBC and NEHRP Judis_dEL

1994NEHRP

3.1 General

3.1.4 SeismicRelativeDisplacement

Changes

The requirements for architectural,mechanical, and electrical componentshave been revised. The exceptions tofollowing the provisions are included.

This new section introduces formulas tocalculate the relative displacement thatmay occur between components.

1997 USC

1632.1General

1632.4RelativeMotion ofEquipmentAttachments

No changes

No changes

Changes Comments

The intent of the sections are similar,however, the exceptions differ. UBCallows exception for furniture and allequipment weighing less than 400pounds. NEHRP allows exceptionsbased on seismic performancecategOlY, importance factor, and inone case, weight and location ofmounting. UBC is more stringent inmost cases because there are noexceptions that are based on seismiczones. Thus, the sections areequivalent.

Both documents requireconsideration of relative motion,although, the method of calculating itdiffers. NEHRP bases thedisplacement on the smaller oftheactual or the allowable whereas UBCrequires calculation based on theactual displacement. Thus, thesections are equivalent.


1994NEHRP Changes 1997 USC Changes Comments

4.2.2 Soil No changes 1809.2 Soil A previous provision allowed a one- Since NEHRP also allows the one-Capacity Capacity third stress increase to be third increase to be exceeded, the

exceeded for soils in combination sections are equivalent.with earthquake when substantiatedby geotechnical data. The 1997code no longer allows this.


Table 2B: Ch dP UBC d NEHRP Judaed E t1994 NEHRP Changes 1997 UBC Changes Comments

4.4.3 The design loads for foundation ties are 1807.2 No changes The loads in NEHRP are only largerFoundation revised because of the change in Interconnec- than UBC when Ca is greater thanTies seismic coefficients. tion 0.4. This will occur when Aa=0.4 and

soil profile type D exists. With onlyone exception, the sections areessentially equivalent.

No equivalent section 1806.2 & Consideration for expansive soils is Since NEHRP does not require1806.3 a new requirement. consideration for expansive soils, theFooting sections are equivalent.Design andBearing Walls

No equivalent section 1806.7 This section includes new Since NEHRP does not have similarSeismic provisions that require minimum requirements for minimum amountsZones 3 and 4 amounts of reinforcement in of reinforcement, the sections are

foundations with stemwalls and equivalent.slabs on ground with turned downfootings.

No equivalent section 1816.4 In the new code, the design Since NEHRP does not have similarStructural procedure for post-tensioned slabs provisions, the sections areDesign may also be used for stiffening equivalent.Procedure for beams or uniform thicknessSlabs on foundations.ExpansiveSoils

No equivalent section 1819 Design This new section indudes Since NEHRP does not have similarof Post- provisions to design posttensioned provisions, the sections aretensioned slabs on compressible soils. equivalent.Slabs onCompressibleSoils

No equivalent tables Tables 18-11I- Values of differential swell for Since NEHRP does not have similarA-DD velocity of moisture flow for 0.1 and tables, the sections are equivalent.

0.3 inches/month were deleted.


Chl:S~i?t.ErOViSions in USC and NEHRP Jud

1994NEHRP


5.2 StructuralSteel SeismicRequirements

Changes

Seismic Provisions for Structural steelBuildings by AISC was added as areference, and as a result, the length ofthis chapter was reduced. Part I isbased on AISC LRFD and Part II isbased on AISC ASD. Updated versionsof LRFD by AISC and StandardSpecification, Load Tables and weightTables for Steel Joists and Joist Girdersare referenced. Another new referenceis Load and Resistance Factor DesignSpecification for Cold-formed StainlessSteel Structural Members.

The design of structural steel membersand connections to resist seismic forcesshall be in accordance with ASD andLRFD.

1997 UBC

2206Adoption

Division IVSeismicProvisions forStructuralSteelBuildings

Division VILoad andResistanceFactor DesignSpecificationfor ColdFonned SteelStructuralMembers

Division XIDesignStandard forStructuralApplicationsof SteelCables forBuildings

2204 DesignMethods

Changes

The 1993 edition of the LRFD wasadopted (previously it was 1986)with minimal amendments.

The 1992 edition of SeismicProvisions for Structural SteelBuildings by AISC withamendments was adopted.

The 1991 edition of Load andResistance Factor DesignSpecification for Cold-Formed SteelStructural Members was adoptedwith some modifications.

The 1995 edition of StructuralApplications ofsteel Cables forBuildings by ASCE was adopted.

UBC states that design should be inaccordance with LRFD and ASD.

Comments

Both documents refer to the LRFD,ASD, Seismic Provisions forStructural Steel Buildings, and Loadand Resistance Factor DesignSpecification for Cold-Formed SteelStructural Members.

NEHRP adopted The Criteria forStructural Applications for steelCables for Buildings by AISI 1973edition.

Since the main design specificationsare similaJ1y referenced in bothdocuments, the main design intent ofthe provisions are equivalent.

Since both documents refer to thesame design manuals, the designcriteria are equivalent.

UBC - 97- NIST Code Comparison

1994NEHRP

5.2.1 RequirementsforSpecialConcentricallyBracedFrames


This section includes the modifications to 2210 This section includes the NEHRP and UBC madethe requirements of Seismic Provisions Amendments modifications to the requirements of modifications to the requirements forfor structural Steel Buildings. Seismic Provisions for Structural specially concentrically braced

Steel Buildings. frames that are essentiallyequivalent. UBC contains moremodifications than NEHRP becauseof the difference in variables used.

5.3 ColdFormed SteelSeismicRequirements


This section references SeismicProvisions for Structural Steel BUildings(1992), Specification for the Design ofCold-Formed Steel Structural Members(1986), and Load and Resistance FactorDesign Specification for Cold-FormedSteel Structural Members (1991).Modifications to the references areincluded. The most notable modificationis the use of an earthquake load factor of1.0 instead of 1.5.

Specification for the Design ofColdFormed Steel structural Members, Loadand Resistance Factor DesignSpecification for Cold-Formed SteelStructural Members and Specification forthe Design ofCold-Formed StainlessSteel Structural Members arereferenced.

The requirements for eccentricallybraced frame web stiffeners may befound in section 10.3 of SeismicProvisions for Structural Steel Buildings.

Division VI &VII Specification for Designof Coldformed SteelStructuralMembers

Division VIIILateralResistance forSteel StudWall Systems

2213.10.9Web StiffenerSpacing

This section adopts and modifiesLoad and Resistance Factor DesignSpecification for Cold-Formed SteelStructural Members (1991) andSpecification for Design ofColdFormed Steel Structural Members(1986).

This section expands on previousrequirements for steel stud walls.New tables are provided that givethe lateral resistance of varioustypes of steel stud walls.

The spacing of the web stiffener isdependent on link beam rotation.One of the limits was changed from0.06 to 0.09 radians which makesthe requirement for stiffeners less.

Both documents use the samereferences. Besides minordifferences in modifications that thedocuments made to the references,the main difference is the use of anearthquake load factor of 1.0 inNEHRP. Since UBC will have higherloads and the reference documentsare the same, the sections areequivalent.

The references in NEHRP arereferred to in other divisions oftheUBC steel chapter. The additionalrequirements that NEHRP gives areincluded in UBC. Thus, the sectionsare equivalent.

With the change in UBC, the limit onlink beam rotation is equivalent.Thus, the sections are equivalent.


1994 NEHRPTable 2B: Changed Provisions in UBC and NEHRP Judged Equivalent


No equivalent provision I 2213.11 This new section indudes Since NEHRP does not haveRequirements provisions for designing special provisions for special truss momentfor Special truss moment frames. frames, the sections are equivalent.Truss MomentFrames


1994 NEHRP Changes 1997 UBC Changes

6.1 Reference The revised version of AC1318-89 is Division II UBC is in conformance with ACIDocuments used as a reference. The revised 318-95 (with modifications).

version indudes Building Code Requirements for Structural PlainRequirements for Structural Plain Concrete are induded.Concrete.

6.1.1.4 IRequirements for precast elements that 1921.2.1.6 Requirements for precast elementsare part of the lateral-force-resisting that are part of the lateral-force-system were added. resisting system were added.

6.1.1.5 I Requirements for connections of precast 1921.2.2.5-7 Requirements for connections ofconcrete elements that emulate the precast concrete elements thatbehavior of monolithic reinforced emulate the behavior of monolithicconcrete construction were added. reinforced concrete construction

were added.

6.1.1.7 IRequirements for strong connections of 1921.2.7 Requirements for strongprecast concrete frames were added. connections of precast concrete

frames were added.

6.1.1.12 This section contains additional 1921.6.12 This section contains additionalrequirements for concrete diaphragms. Diaphragms requirements for concrete

diaphragms.

Comments

Since UBC references a later versionof AC1318, UBC is at leastequivalent to and possibly morestringent than NEHRP. Thus, thesections are equivalent.

The provisions in the sections areequivalent.

The provisions in the sections areequivalent.

Many provisions are equivalent,however UBC has additionalrequirements regarding anchorage,splicing, etc. Thus, the sections areequivalent.

The documents are similar in intent,however, UBC has additionalprovisions regarding mechanicalconnectors, prestressing tendons,etc. Thus, the sections areequivalent.


Table 2B: Ch dP UBC d NEHRP Judaed E t.... .1994 NEHRP Changes 1997 UBC Changes Comments

6.1.1.13 Provisions for coupling beams were 1921.6.10 Provisions for coupling beams were The provisions are equivalent.added. Coupling added.

Beams

6.2.3 Strength The strength reduction factor for anchors 1923.3.1 A phi factor of 0.65 is specified but Since the specified phi factor in USCBased on shall be 0.8 when the anchor failure General may be 0.85 when the anchor is produces nominal capacities that areTests governs in the majority attests and 0.65 1923.3.2 attached to or hooked around equivalent to or less than NEHRP,

when the concrete failure controls. Design reinforcing steel or otherwise the sections are equivalent.

Strength in terminated to effectively transfer

Tension forces to the reinforcing steel.

6.2.4 Strength The formula to calculate the tensile 1923.3 The formulas to calculate the The formulas for strength in tensionBased on strength governed by concrete failure Strength of design strength in tension were are similar, however NEHRPCalculations was revised. Two formulas which Anchors revised. provides formulas for different

depend on the spacing of the anchors conditions of grouping. UBC gives aare given. description of the failure surface

which will occur ifthe anchors arespaced closely. The result would bea formula equivalent to that given inNEHRP. Thus, the sections areequivalent.

6.2.4.3 The interaction equations to check the 1923.3.4 One of the interaction equations to The one equation that is not theCombined capacity for a combination of tension and Combined check the capacity for a same in the documents is moreTension and shear were revised. The result of the Tension and combination of tension and shear stringent in UBC. Thus, the sectionsShear change is less stringent interaction Shear was revised. The result of the are equivalent.

equations. change is a more stringentinteraction equation.

6.5.1 Ordinary New requirements for ordinary moment 1921.3.2.1 No changes The sections are equivalent.Moment frames with seismic performanceFrames category Bwere added.

6.7.4 Plain A new provision states that structural 1922.10 No changes UBC states that structural membersConcrete members of plain concrete are not Seismic of plain concrete are not permitted in

permitted in buildings assigned to Requirements seismic zones 2, 3 and 4 (with somecategory D or E (with some exceptions). for Plain exceptions). The limits that NEHRP

Concrete and UBC give are equivalent


td NEHRP Judaed EUBCdPTable 2B: Ch ...1994 NEHRP Changes 1997 UBC Changes Comments

Appendix to A new appendix was added to introduce 1921.2.1.6 Requirements for precast elements Requirements in section 1921.2.1.6Chp.6 provisions for structural systems that are part of the lateral-force- are equivalent to section 6.1.1.4 inReinforced composed of precast concrete elements resisting system were added. NEHRP. Although UBC does notConcrete interconnected with dry connections. have equivalent provisions, theStructural appendix in NEHRP is just anSystems introduction to the systems.Composed Therefore, the sections may befrom Intercon- considered equivalent.nectedPrecastElements

No equivalent provision 1921.2.1.7 Requirements for precast gravity Since NEHRP does not have similarsystems and its connections were provisions for precast gravityadded. systems, the sections are equivalent.

No equivalent provision 1921.2.6 Additional requirements relating to Since NEHRP does not have similarwelded splices and mechanically requirements, the sections areconnected reinforcement were equivalent.added.

No eqUivalent provision 1921.4.4.8 Requirements for ties at anchor Since NEHRP does not have similarTies at Anchor bolts that are set in the top of a requirements, the sections areBolts column were added. eqUivalent.

No equivalent provision 1921.6.6.2 The provisions for the effective Since NEHRP does not provisions forflange width to design a shear wall effective flange widths, the sectionswere revised. The revision may are equivalent.result in a longer effective flangewidth.

No equivalent provision 1921.6.7.3 Requirements for reinforcement in Since NEHRP does not have similarchords and collectors at splices and requirement, the sections areanchorage zones were added. equivalent.


1994 NEHRPTable 2B: Changed Provisions in UBC and NEHRP Judged Equivalent


No equivalent provision I Division VII A new division was added that Since no equivalent provision existsUnified includes unified design provisions in NEHRP, the sections areDesign for reinforced and prestressed equivalent.Provisions concrete flexural and compression

members.


1994 NEHRP


7.5CompositeMembers

Changes

The reference documents are listed inthis section.


1997 UBC

Chapter 19Concrete

Chapter 22Steel

Chapter 19ConcreteChapter 22Steel

Changes



Comments

The documents that NEHRP andUSC reference are equivalent.

Since NEHRP and USC have thesame references, the sections areequivalent.


1994NEHRP

8.1 General

8.1.2ReferenceDocuments

Changes


Thirty-fIVe material standard referenceswere added.

1997 UBC

2102.2StrengthDesign

2102.2Standards ofQuality

Changes

No changes

There were slight changes to thematerial standards references.

Comments

Since USC includes provisions forworking stress and strength design,the design approaches areequivalent.

Although both codes have a similarnumber of references, the referencesdo not necessarily match. Even so,the sections are jUdged to beessentially equivalent.


1994NEHRP

8.3.9 SeismicPerformanceCategory E

8A.8.1ConstructionRequirements


The requirement for solid grouting of 2104.4.4 No changes UBC does not require solid groutingstructural masonry that is not part of the Hollow- of structural masonry that is not partseismic resisting system was removed. masonry Units of the seismic resisting system. UBC

2106.1.12.4 requires all head and bed joints to beSpecial ~lIed solid with mortarfor.a distanceProvisions for In from the face of the umt not lessSeismic than the thickness of the shell.Zones 3 and 4 Therefore, the sections are

equivalent.

8.3.10Properties ofMaterials

8.3.12 Plate,Headed andBent BarAnchor Bolts

UBC

The table which contained values of themodulus of elasticity (8.3.10.2) wasremoved in lieu of calculating themodulus using Eq. 8.3.10.2. The valuesof modulus of rupture in Table 8.3.10.5.1were revised.

The calculations for the design axial andshear strengths were revised (Eq.8.3.12.1-1,8.3.12.1-2,8.3.12.2-1,8.3.12.2-2).

2106.2.12.1Modulus ofElasticity ofMasonry

2108.2.4.6DeflectionDesign

2108.1.5.2NominalAnchor BoltStrength

No changes

One ofthe formulas for the nominaltensile capacity of an anchor boltwas revised. The capacity wasreduced since the area oftheanchor bolt replaced the area of thepullout cone. Similar1y, for nominalshear capacity, the area of theanchor bolt replaced the area of theeffective cross-sectional area ofreinforcement.

·103·

The formula to calculate the modulusof elasticity of masonry is equivalentin the documents. NEHRP givesvalues for the modulus of rupturebased on whether it is normal orparallel to the bed joints, the type ofmortar that is used, and the type ofmasonry unit. UBC bases themodulus on the compressive strengthand the type of masonry unit.NEHRP will typically give lowervalues for the modulus of rupture,therefore the sections are equivalent.

In most cases the anchor boltnominal strength in NEHRP is largerthan UBC. Thus, UBC is morestringent and the sections areequivalent.


td NEHRP Judaed EUBCdPTable 2B: Ch ..1994NEHRP Changes 1997 USC Changes Comments

8.5.1 General No changes 2108.1.3 The load combinations that were Since both codes reference loadRequired previously defined in this section combinations in the generalStrength and now are referenced to the load provisions chapters, the sections are

combinations in chapter 16. equivalent.

8.6.2 Design The critical strain ratio was reduced from 2108.2.3.7 No changes The maximum reinforcement ratioRequirements 0.003 to 0.002. The critical strain ratio is Reinforce- allowed in UBC is half oftheof Reinforced used to calculate the maximum ment balanced reinforcement ratio. SinceMasonry reinforcement ratio. 2108.2.4.2 the maximum reinforcement allowedMembers Maximum in UBC is less than NEHRP, UBC is

Reinforce- more stringent. The sections are

ment equivalent.

8.6.3 Design The allowable flexural compressive 2107.3.2 No changes In allowable stress design, UBCof Plain stress for unreinforced masonry in non- Allowable places the allowable compressiveUnreinforced seismic applications is now proportional Axial stress at 0.33fm. Although the limitMasonry to the strain up to 0.85fm. The previous Compressive in NEHRP is at an ultimate strengthMembers version limited this condition to 0.33fm. Stress level, at an equivalent level, NEHRP

would probably still be higher. Thus,UBC is more stringent and thesections are equivalent.

8.7.2 Shear The 2/3 factor that was applied to shear 2108.2.3.5 No changes With the change to NEHRP, theStrength strength when comparing it to the shear Design codes are equivalent in comparing

demand was removed. Strength factored demand to nominal strength.

8.11.2 The requirement for confinement was 2108.2.5.6 No changes UBC requires boundary members toConfinement changed from a strain limit to the plastic Boundary be provided when the strain exceedsof hinge zone regions. The definition of a Members 0.0015. Although the change inCompressive confined compressive zone was added. NEHRP provides a more qualitativeStress Zone definition, the intent is similar and the

sections are essentially equivalent.


Table 28: Ch dP U8C d NEHRP Judaed E t.1994 NEHRP Changes 1997 USC Changes Comments

8.11.3 A requirement was added that states that 2106.2.6 No changes USC allows for the effective flangeFlanged solid units shall be laid in running bond Effective width to be 6 times the thickness ofShear Walls and 50% of the masonry units at wall Width of the intersected wall on each side.

intersections shall be interlocked. The Intersecting Unlike NEHRP, there is no distinctioneffective width of flange in compression Walls of the width for tension versuswas changed from 1/6 ofthe wall height compression. Since the effectiveto 9 times the thickness of the web. The flange width in USC is smaller, USCeffective width of flange in tension was is more stringent. Thus, the sectionschanged from 1/3 of the wall height to are equivalent.3/4 of the wall height.

8.12 Wall The requirement of where plastic hinges No equivalent provision Since NEHRP removed theFrames shall be formed was removed. provision, the sections are

equivalent.

8.12.4 A new restriction requires that actual 2108.2.6.2.4 No changes USC states that the actual yieldReinforce- yield strength shall not exceed 1.5 times Reinforce- strength shall not exceed the 1.3ment the nominal yield strength. ment times the specified yield strength,

whereas it is 1.5 in NEHRP. ThusUSC is more stringent and thesections are equivalent.

8.12.5 Wall An additional restriction that the 2108.2.6.2.5 No changes The maximum reinforcement inFrame Seams reinforcement ratio shall be less than Flexural beams in the documents is

0.15fmify was added. The maximum Members equivalent. The maximum spacing ofspacing of transverse reinforcement was (beams) transverse reinforcement is alsoincreased from 1/4 of the beam depth to equivalent.1/2 ofthe beam depth.

8.12.6 Wall The limit of factored axial compression 2108.2.6.1.2 No changes The limit on factored axialFrame force was changed from 0.30Anfm to Dimensional compression force is equivalent. TheColumns 0.15Anfm. The limit of minimum column Limits minimum nominal depth of a pier in

dimension was decreased from 32 2108.2.6.2.7 USC is two full units or 32 inches,inches to 24 inches. Pier Design whereas it is 24 inches in NEHRP.

Forces There USC is more stringent and thesections are equivalent.


1994NEHRP

8.12.7 WallFrame SeamColumnIntersection

Table 2B: Changed Provisions in UBC and NEHRP Judged EquivalentChanges I 1997 USC I Changes I Comments

The definition ofthe dimension of the 2108.2.6.2.9 No changes The formulas for the dimension ofthebeam-column intersection was changed Joints pier are equivalent. The formula infrom a multiple ofthe bar diameters to NEHRP will give a beam depth that isEq. 8.12.7.1-1 and Eq. 8.12.7.1-2. A over 2 times larger than USC. USCrestriction that the shear stress shall not is more stringent since it will produceexceed 7 roots fm was added. a smallerjoint. Therefore the

sections are equivalent. Similar toNEHRP, USC has a provision to limitthe shear strength to 7 roots fm.

CHAPTER 9: WOOD STRUCTURE DESIGN REQUIREMENTS

1994NEHRP


9.2 Strengthof MembersandConnections

Changes


The factor to multiply the allowableworking stress has been increased from2.0 to 2.16. The phi factors have beenrevised. The phi factor was reduced formembers in flexure with compression.The categories of connectors have beenrevised. The phi factor was reduced forshear on diaphragms and shear walls.In general, with the increase in capacityand decrease in phi factor, the resultingnominal capacity is lower.

1997 USC

2303Standards ofQuality

2316.1Adoption andScope

2301.2.1AllowableStress Design

Changes

Standards are referenced forvarious aspects of wood design.The 1991 edition ofthe NOS isadopted for the allowable stressdesign of wood. In the previouscode, NOS was incorporated butnot specifically adopted.

No changes

Comments

Since the reference to 1991 NOS isconsistent in both documents, designspecifications are essentiallyequivalent. Although some of thematerial references are similar, forthe most part the references in thedocuments are not the same. Evenso, the sections are judged to beessentially equivalent.

USC uses allowable stress design forwood. Using the strength increaseand phi factors in NEHRP, thestrength is increased more than thevalue of the load factors. Therefore,since NEHRP capacities are higherrelative to the demand, the sectionsare equivalent.


td NEHRP Judaed EUBCdPTable 2B: Ch ·1994NEHRP Changes 1997 USC Changes Comments

9.10.2.1 Wall No changes 1806.6 The size of steel bolt required was The bolt size required in seismicAnchorage Foundation increased for seismic zone 4. zone 4 in USC is larger than NEHRP.

Plates or Sills Thus, the sections are equivalent.

No equivalent provision 2315.1 The height of a shear wall is defined NEHRP does not specifically addressGeneral and guidelines for designing a the design of a shear wall with

shear wall with openings are openings. Thus, the sections areincluded. equivalent.


ad Provisions in sse and NEHRP Jud

1994 NEHRP Changes 1997 SSC Changes Comments

1.2 Scope This section lists structures that are 1607.1 This section allows the loads to be The 1997 SSC deviates significantlyexceptions to seismic design provisions. General determined from this section or here due to the fact it did not adoptExceptions for one and two family ASCE 7-95. This change was the Ca and Cv factors used in thedwellings that were previously incorporated because SSC did not 1994 NEHRP. Thus, NEHRP isdependent on Av, were revised to adopt the Ca and Cv factors of the more stringent and the sections aredepend on a new coefficient Ca. 1994 NEHRP or ASCE 7-95. The not equivalent.

1997 SSC still uses the Aa and Avfactors from the 1991 NEHRP.

1.4.2 Seismic Six new soil profile types are defined in 1607.3.1 Site No changes Since SSC did not adopt the changesCoefficients this section where previously there were Coefficient made to NEHRP, using NEHRP will

4. Seismic coefficients Ca and Cv, which result in higher seismic forces for softdepend on soil profile and seismic zone, soils, especially in regions of loware introduced in this section. Ca and Cv seismicity. Thus, NEHRP is morereplace AaS and Av in the 1991 stringent and the sections are notprovisions. All provisions that were equivalent for soft soils.previously related to Av and Aa wererevised to reflect the new coefficients.

1.4.4 Seismic The seismic performance category for 1607.1.7 No changes Since SSC did not adopt the changesPerformance seismic hazard exposure group III Seismic made to NEHRP, NEHRP is moreCategory buildings with values of Av ranging from Performance stringent. Thus, the sections are not

0.10 to 0.15g was increased from Cto 0 Category equivalent.to reduce the risk of collapse in essentialservice buildings in regions of moderateseismicity.

1.6 Quality Quality assurance provisions now apply 1708 Seismic No changes For other designated seismicAssurance to other designated seismic systems in Inspections systems, SSC only requires

seismic performance category D. and Testing inspection in Category E. Thus,NEHRP is more stringent and thesections are judged not equivalent.


1994 NEHRP

1.6.2.1FoundationSpecialInspection

Table 3A: Changed Provisions in SSC and NEHRP Judged Not EquivalentChanges I 1997 SBC I Changes I Comments

The requirement for continuous special 1780.7 No changes SSC only requires that inspection isinspection for placement of concrete was Foundations required. Thus, by requiringadded. The requirement for continuous continuous inspection for placementspecial inspection for construction of of concrete, NEHRP is moredrilled piles and caissons was changed stringent and the sections are judgedto periodic inspection. The requirement not equivalent.for periodic inspection for placement ofreinforcing steel was added.

1.6.2.4SpecialInspection ofPrestressedConcrete

1.6.2.6.1SpecialInspection ofStructuralSteel Welding


The requirement for special inspectionafter the completion of placement ofprestressing steel was added.

An exception to continuous specialinspection in lieu of periodic inspectionfor welds loaded to less than 50 percentof their design strength was added.

The criteria for requiring specialinspection changed from theperformance criteria factor P, whichdepends on seismic hazard exposuregroup and the item to be braced, to theseismic performance category, whichdepends on Av and seismic hazardexposure group. Exceptions to periodicspecial inspection were added andadditional items requiring inspection wasadded.

1708.4ReinforcedConcrete

1708.2StructuralSteel Welding

1708.8 WallPanels andVeneers

No changes

No changes

No changes

Since SSC did not make thismodification, NEHRP is morestringent. Thus, the sections arejudged not equivalent.

Inspection of structural steel weldingin SSC consists of ultrasonic testing.However, the testing is required oncertain elements, not for all welding.Thus, NEHRP is more stringent andthe sections are judged notequivalent.

Since SSC only requires inspectionin seismic performance category Eand has retained the performancecriteria P, NEHRP is more stringentand the sections are jUdged noteqUivalent.


1994 NEHRP

1.6.2.9SpecialInspection ofMechanicaland ElectricalComponents

Table 3A: Changed Provisions in SBC and NEHRP Judged Not EquivalentChanges I 1997 SBC I Changes I Comments

The criteria for requiring special 1708.9 No changes Since SBC only requires inspectioninspection changed from performance Mechanical in seismic performance category Ecriteria P to seismic performance and Electrical and has retained the performancecategory (see above). The items Components criteria P, NEHRP is more stringentrequiring special inspection were revised. and the sections are judged not

equivalent.


1994NEHRP Changes 1997SBC Changes Comments

2.2.5.1.2 Although there were no changes in this 1607.3.6.1.2 No changes Since SBC did not adopt the changeAnchorage of section, the formula to calculate the Concrete or to the anchorage force, the change inConcrete or anchorage force in section 3.1.3 was Masonry Wall NEHRP will result in a higherMasonry revised. Anchorage anchorage force. Thus, NEHRP isWalls more stringent and the sections are

not equivalent.

2.2.6 Load combinations are referenced to No equivalent section Since SBC has no provisionsCombination ANSIIASCE 7-93 which differ from the regarding combination of load effects,of Load previously given combinations. In NEHRP is more stringent. Thus, theEffects earthquake load combinations, the dead sections are not equivalent.

load factor is slightly higher but the liveand snow load factors are typically lower.The vertical earthquake loads depend onCa where they previously depended onAv. The new vertical loads will be lessfor soil profile A, equivalent for soil type Band in most cases they will be larger forsoil types C, 0 and E.

2.2.7 The category for single story buildings in Table No changes By not incorporating the changesDeflection and the allowable drift limit table was deleted. 1607.3.8 made to NEHRP, masonry shearDrift Umits Previously there was no limit on the Allowable walls designed to the 1997 SBC are

allowable drift for single story buildings in Story Drift allowed a greater drift. Thus, NEHRPseismic hazard exposure group I. New is more stringent and the two tablesstringent allowable drift limits have been are judged not equivalent.specified for masonry buildings.


Table 3A: Ch dP SSC d NEHRP Judaed Not E t1994NEHRP Changes 1997SSC Changes Comments

2.3.2.1 In calculating Cs, the seismic response 1607.4.1.1 No changes Since SSC did not adopt the changeCalculation of coefficient, Cv replaces AvS and Ca Calculation of to the seismic response coefficient,Seismic replaces Aa in the equations. Using Seismic NEHRP results in higher seismicResponse these new coefficients, the base shear is Response forces for buildings on soft soils.Coefficient lowered for structures on rock but is Coefficient Thus, NEHRP is more stringent and

increased for structures on soft soils. the sections are not equivalent.The base shear of a structure is V=CsW.

2.6 Provisions This is a new section based on the 1994 No equivalent section SSC has no specific provisions forfor Seismically USC Appendix Chapter 16, division III. seismically isolated structures. WhileIsolated The provisions have been modified to SSC does not prohibit this type ofStructures conform to the strength based design design, it is silent on the approach to

approach and nomenclature ofthe take to design a seismically isolateddocument. structure. Therefore, NEHRP is more

restrictive and the sections are notequivalent.

2.6.2.3 All portions of the building shall be No equivalent section SSC has no specific provisions forSeismic assigned a Seismic Hazard Exposure seismically isolated structures. WhileHazard Group SSC does not prohibit this type ofExposure design, it is silent on the approach toGroup take to design a seismically isolated

structure. Therefore, NEHRP is morerestrictive and the sections are notequivalent.

2.6.2.5.2 The provisions for using the equivalent No equivalent section SSC has no specific provisions forEquivalent lateral force procedure are included in seismically isolated structures. WhileLateral Force this section. SSC does not prohibit this type ofProcedure design, it Is silent on the approach to

take to design a seismically isolatedstructure. Therefore, NEHRP is morerestrictive and the sections are notequivalent.

SSC -iii - NIST Code Comparison

Table 3A: Ch dP SSC d NEHRP Judaed Not E t1994 NEHRP Changes 1997 SSC Changes Comments

2.6.2.5.3.3 The criteria that would require a site No equivalent section sse has no specific provisions forSite Specific specific design spectra analysis is seismically isolated structures. WhileDesign included in this section. sse does not prohibit this type ofSpectra design, it is silent on the approach to

take to design a seismically isolatedstructure. Therefore, NEHRP is morerestrictive and the sections are notequivalent.

2.6.6.2.8 Access for inspection and replacement No equivalent section sse has no specific provisions forInspection of the isolation system shall be provided. seismically isolated structures. Whileand sse does not prohibit this type ofReplacement design, it is silent on the approach to

take to design a seismically isolatedstructure. Therefore, NEHRP is morerestrictive and the·sections are notequivalent.

2.6.9.3 This section includes a formula to No equivalent section sse has no specific provisions forDetermination calculate the effective stiffness of an seismically isolated structures. Whileof Force isolation system. sse does not prohibit this type ofDeflection design, it is silent on the approach toeharacteris- take to design a seismically isolatedtics structure. Therefore, NEHRP is more

restrictive and the sections are notequivalent.

2.6.9.4 This section includes the criteria to judge No eqUivalent section sse has no specific provisions forSystem adequacy in test specimens. seismically isolated structures. WhileAdequacy sse does not prohibit this type of

design, it is silent on the approach totake to design a seismically isolatedstructure. Therefore, NEHRP is morerestrictive and the sections are noteqUivalent.


1994 NEHRP


Table 3A: Changed Provisions in SSC and NEHRP Judged Not EquivalentChanges I 1997 SBC I Changes I Comments

This new section includes requirements No equivalent section SSC has no specific provisions forto design all self-supporting structures, nonbuilding structures. While SSCother than bUildings, bJidges and dams, does not prohibit this type of design,that are supported by the earth, that it is silent on the approach to take tocarry gravity loads, and that may be design a seismically isolatedrequired to resist the effects of an structure. Therefore, NEHRP is moreearthquake. restrictive and the sections are not

equivalent.



3.1 General The requirements for architectural, 1607.6 No changes Since SSC did not revise this sectionmechanical, and electrical components Architectural, to include the new provisions,have been revised. The exceptions to Mechanical, NEHRP is more stringent and thefollowing the provisions are included. and ElectJical sections are not equivalent.

Componentsand Systems

3.1.3 Seismic PreviOUSly, lateral force calculations for 1607.6.3 This section added an exception to Since SSC did not revise theForces architectural and mechanical/electrical Architectural seismic forces for architectural formulas, the NEHRP formulas will

equipment were separated. In the new Component component design of storage racks. result in higher seismic forces forprovisions, general formulas for all Design The formulas used are still from the nonstructural components. Thus,equipment are provided. The formulas 1607.6.4 1991 NEHRP. NEHRP is more stringent and thedepend on Ca, importance factor of the Mechanical, sections are not equivalent.equipment, component amplification, Electricalresponse factolS, and vertical location of Componentthe equipment in the building. and System

Design

3.1.4 Seismic This new section introduces formulas to No equivalent section Since SSC has no provision, NEHRPRelative calculate the relative displacement that is more stringent. Thus, the sectionsDisplacement may occur between components. are not eqUivalent.


Table 3A: Ch dP SBC d NEHRP Judaed Not E t1994 NEHRP Changes 1997 SBC Changes Comments

3.1.5 New importance factors are introduced Table No changes Since SSC did not revise this section,Component which depend on the severity of failure of 1607.6.3 NEHRP is more stringent. Thus, theImportance the component. Table sections are not equivalent.Factor 1607.6.4A

3.2.6 This new section outlines additional 1607.6.3.3 No changes Since SSC did not revise this section,Suspended requirements for bracing suspended Ceilings NEHRP is more stringent. Thus, theCeilings ceilings. sections are not equivalent.

Design and construction references andminimum clearances are among theadditional requirements.

3.2.7 Access This new section outlines additional No equivalent section Since SSC has no provision, NEHRPFloors requirements for bracing access floors. is more stringent. Thus, the sections

The weight used to calculate loads and are not equivalent.the requirements for special accessfloors are included.

3.2.9 steel This new section outlines additional No equivalent section Since SSC has no provision, NEHRPStorage requirements for bracing steel storage is more stringent. Thus, the sectionsRacks racks. The weight used to calculate are not equivalent.

loads and the response factor to designstorage racks is included.

3.3 Extensive requirements for bracing 1607.6.4 No changes Since SSC did not revise this section,Mechanical various mechanical and electrical Mechanical, NEHRP is more stringent. Thus, theand Electrical components such as piping, elevators, Electrical sections are not eqUivalent.Components and storage tanks are proVided. Component

and SystemDesign


ed Provisions in SSC and NEHRP Jud_CL_U.S_CEUI_C.ZSLhZ_dS-dUU_d_dCL

1994NEHRP

4.4.3FoundationTies

Changes


1997SBC

1804.5FootingSeismic Ties

No changes

Changes Comments

The loads in NEHRP are larger whenCa is greater than 0.4, which occursin regions of high seismicity with softsoils. Since no change was made toSSC, NEHRP is more stlingentunder these conditions. Thus, thesections are not equivalent in highseismic zones on soft soils.


1994 NEHRP Changes 1997SBC Changes Comments

6.1.1.5 Requirements for connections of precast 1912.1.1 No equivalent modification Since SSC does not have thisconcrete elements that emulate the Modifications modification, the modification resultsbehavior of monolithic reinforced to in NEHRP being more stringent.concrete construction were added. Thus, the sections are not equivalent.

AC1318-95

6.1.1.7 Requirements for strong connections of 1912.1.1 No equivalent modification Since SSC does not have thisprecast concrete frames were added. Modifications modification, the modification results

to AC1318-95 in NEHRP being more stringent.Thus, the sections are not equivalent.

6.1.1.8 This section includes provisions for 1912.1.1 No equivalent modification Since SSC does not have thiscalculating the probable capacities of Modifications modification, the modification resultsstructural elements in precast concrete to ACI 318-95 in NEHRP being more stringent.frames. Thus, the sections are not equivalent.

6.1.1.12 This section contains additional 1912.1.1 No equivalent modification Since SSC does not have thisrequirements for concrete diaphragms. Modifications modification, the modification results

to ACI 318-95 in NEHRP being more stringent.Thus, the sections are not eqUivalent.


td NEHRP Judaed Not ESBCdPTable 3A: Ch ...1994NEHRP Changes 1997 sec Changes Comments

6.2.2 Strength A provision was added that states that 1914.1.3 No changes SBC does not distinguish theof Anchors anchors shall be detailed so that the Strength of strength of anchors due to failure

connection failure is initiated by the Anchors mode. NEHRP will provide a ductilityfailure ofthe anchor steel rather than by failure mode, while SBC may not.the failure of the surrounding concrete. Thus, the sections are not equivalent.

6.2.3 Strength The strength reduction factor for anchors 1914.1.3 No changes Since SBC does not distinguish theBased on shall be 0.8 when the anchor failure Strength of strength of anchors due to failureTests governs in the majority of tests and 0.65 Anchors mode, there are no strength reducing

when the concrete failure controls. factors. Thus NEHRP is morestringent and the sections are notequivalent.

6.2.4.3 The interaction equations to check the 1914.1.6 No changes SBC was more stringent than theCombined capacity for a combination oftension and Combined previous version of NEHRP.Tension and shear were revised. The result of the Tension and However, with the modifications toShear change is less stringent interaction Shear NEHRP, SBC only has two ofthe

equations. four equations in NEHRP. Thus,NEHRP is more stringent and thesections are not equivalent.

6.5.2 Moment A new provision was added that states No equivalent section Since SBC has no eqUivalentFrames that moment frames on soil profile type E section, NEHRP is more stringent.

or F with seismic performance category Thus, the sections are not equivalentB shall be an intermediate moment for seismic performance category Bframe. moment frames on soil types E and

F.

sec -116 - NIST Code Comparison

Table 3A: Cha~,~;1sE[?:!:1g.~~L~;~c~~:s'Mt~:,~§E;1~2

7.2 Reference IThe reference documents are listed inDocuments this section.

1994NEHRP


7.4CompositeSystems

7.5CompositeMembers

sac

Changes


Requirements to design compositesystems (partially restrained frames,ordinary. moment frames, specialmoment frames, concentrically bracedframes, eccentrically braced frames,reinforced concrete walls composite withsteel elements and composite shearwalls) are in this section. The sectionoutlines the design requirements forindividual elements of the system.


1997 sac Changes





-117 -

Comments

There is no equivalent sectionregarding composite design in SSC.In addition, although not prohibitingcomposite design, SSC is silent onany specific approach to take indesigning a structure using acomposite lateral-foree-resistingsystem. Therefore, NEHRP is morestringent and the sections are notequivalent.

Since there is no equivalent sectionregarding composite design in SSC,NEHRP is more stringent. Thus, thesections are not equivalent.




td NEHRP Judaed Not ESSCdPTable 3A: Ch ...1994NEHRP Changes 1997 SBC Changes Comments

7.5.2 Additional requirements for special No equivalent section Since there is no equivalent sectionComposite moment frames are given as follows. A regarding composite design in SSC,Seams maximum distance from the maximum NEHRP is more stringent. Thus, the

concrete compression fiber to the plastic sections are not equivalent.neutral axis is given. Compressionelements that are fully encased by areinforced concrete cover (min 2') do notneed to meet the width-thickness ratioprovided that concrete is confined byhoop reinforcement in regions whereplastic hinges are expected to occur.

7.5.3 Encased This section references LRFD for the No equivalent section Since there is no equivalent sectionComposite design of encased composite columns. regarding composite design in SSC,Columns Additional requirements for seismic NEHRP is more stringent. Thus, the

performance category C, D and E are sections are not equivalent.given. Most ofthe additionalrequirements are related to concretereinforcing.

7.5.4 Filled This section outlines the requirements for No equivalent section Since there is no equivalent sectionComposite filled composite columns. LRFD is regarding composite design in SSC,Columns referenced and additional requirements NEHRP is more stringent. Thus, the

are given for seismic performance sections are not equivalent.categories D and E.

7.6 This section includes requirements for No equivalent section Since there is no equivalent sectionComposite connections in structures with composite regarding composite design in SSC,Connections or dual steel-concrete systems where NEHRP is more stringent. Thus, the

seismic loads are transferred. sections are not equivalent.


Chanaed Provisions in SSC and NEHRP Jud

1994NEHRP

8.1 General

SBC

Changes


1997 SBC

2115.2General

Changes

This section incorporates ACI530/ASCE 5ITMS 402-95 in itsentirety. Modifications to thisreference were removed in regardsto seismic design.

-119 -

Comments

ACI 530/ASCE 5ITMS 402-95 didincorporate strength design for theseismic provisions. Therefore, themethodology approach is the same.However, rather than develop aseparate set of strength designprovisions, the standard takes theexisting working stress designmethodology and uses load factors,phi factors, and a 3.325 increase ofallowable working stress values. Thedetailing provisions in the standardessentially remain the same. Incomparing ACI530 and NEHRP, theformulas to calculate strengthcapacities appear to be equivalent,although NEHRP tends to be a bitmore restrictive. In the detailingprovisions, similar checks arerequired in both documents.However, NEHRP is more restrictivewith the parameters it sets, such asmaximum size of reinforcement,bundling of reinforcing bars, andhook development lengths in tension.Based on the comparison of ACI 530and NEHRP, NEHRP appears to bemore stringent. Thus, SSC andNEHRP are not equivalent.


Table 3A: Ch dP SSC d NEHRP Judaed Not E t1994NEHRP Changes 1997SBC Changes Comments

8.1.2 Thirty-fIVe material standard references 3502 Eleven ofthe standards referenced Because SBC does not reference allReference were added. Referenced in NEHRP were not referenced in of the standards in NEHRP, theDocuments Standards SBC. However, most of those not sections are not equivalent.

referenced were testing standards However, material standards are notor material standards not related to that critical in tenns of equivalence.masonry.

8.3.8 Seismic The required roughened surface 2115.7 No changes Neither SBC nor ACI 530 have thisPerfonnance exposure for concrete placement next to Seismic requirement. Thus, NEHRP is moreCategory D masonry that is not designed with a Perfonnance stringent and the sections are judged

separation joint was increased from Category D not equivalent.1/16" to 1/8".

8.4.3 Bundling of bars is no longer allowed. 2115.2 SBC uses ACI 530/ASCE 5rrMS ACI 530/ASCE 5rrMS 402-95 allowsPlacement General 402-95 in its entirety. the use of bundled bars. Thus,Limits for NEHRP is more restrictive and theReinforce- sections are not equivalent.ment

8.4.5 Devel- The calculation of embedment length 2115.2 SBC uses ACI 530/ASCE 5rrMS Due to the equation parameters, aopmentof (Eq. 8.4.5.2) was modified. A General 402-95 in its entirety. direct comparison was not possible.Reinforce- requirement for 6 inches of minimum However, the equation in ACIment embedment length for wire was added. 530/ASCE 5rrMS 402-95 only

The calculation of embedment length for considers the diameter of the bar andhooks (Eq. 8.4.5.4.2) was modified. Lap the strength of steel. The equationssplices are no longer allowed in plastic in NEHRP also take into accounthinge zones. clear cover and strength of masonry.

Based on this, the NEHRP may beconsidered more stringent and thesections are not equivalent.

8.5.4 This section was rewritten to be 2115.2 SBC uses ACI 530/ASCE 5rrMS ACI530/ASCE 5rrMS 402-95 doesDefonnation consistent with the defonnation criteria General 402-95 in its entirety. not contain defonnation provisions,Requirements set forth in Chapter 2. only strength provisions. Thus,

NEHRP is more restrictive and thesections are not equivalent.

SBC ·120· NIST Code Comparison

1994NEHRPTable 3A: Changed Provisions in SBC and NEHRP Judged Not Equivalent

Changes I 1997 sec I Changes I Comments


The critical strain ratio was reduced from 12115.2 Issc uses ACI 530/ASCE 5ITMS0.003 to 0.002. The critical strain ratio is General 402-95 in its entirety.used to calculate the maximumreinforcement ratio.

ACI 530/ASCE 5ITMS 402-95 doesnot define a critical strain ratio. Thus,NEHRP is more stringent and thesections are not equivalent.



8.11.3Flanged.Shear Walls

sec

The equations to calculate shear 12115.2strength in both the masonry and Generalreinforcing steel were modified (Eq.8.7.3.2-1,8.7.3.3).

The requirement for confinement was 12115.2changed from a strain limit to the plastic Generalhinge zone regions. The definition of aconfined compressive zone was added.

A requirement was added that states that 12115.2solid units shall be laid in running bond Generaland 50% of the masonry units at wallintersections shall be interfocked. Theeffective width of flange in compressionwas changed from 1/6 ofthe wall heightto 9 times the thickness of the web. Theeffective width of flange in tension waschanged from 1/3 ofthe wall height to3/4 of the wall height.

SSC uses ACI 530/ASCE 5ITMS402-95 in its entirety.



-121 -

ACI 530/ASCE 5ITMS 402-95 usesone equation for calculating the shearcapacity, independent ofthe steelreinforcement provided. NEHRPuses separate equations forcalculating shear capacities ofmasonry and steel. Since NEHRP isthe more accurate ofthe twomethods, is may be considered morestringent. Thus, the sections are notequivalent.

ACI 530/ASCE 5ITMS 402-95 doesnot contain provisions forconfinement of the compressivestress zone. Thus, NEHRP is morerestrictive and the sections are notequivalent.

ACI 530/ASCE 5ITMS 402-95 doesnot contain provisions for flangedshear walls. Thus, NEHRP is morerestrictive and the sections are noteqUivalent.


td NEHRP Judaed Not ESSCdPTable 3A: Ch ... .1994 NEHRP Changes 1997SBC Changes Comments

8.12 Wall The requirement of where plastic hinges 2115.2 SSC uses ACI 530/ASCE 5fTMS ACI 530/ASCE 5fTMS 402-95 doesFrames shall be formed was removed. General 402-95 in its entirety. not contain provisions for wall

frames. Thus, NEHRP is morerestrictive and the sections are notequivalent.

8.12.4 A new restriction requires that actual 2115.2 SSC uses ACI 530/ASCE 5fTMS ACI 530/ASCE 5fTMS 402-95 doesReinforce- yield strength shall not exceed 1.5 times General 402-95 in its entirety. not contain provisions for wall framement the nominal yield strength. reinforcement. Thus, NEHRP is

more restrictive and the sections arenot equivalent.

8.12.5 Wall An additional restriction that the 2115.2 SSC uses ACI 530/ASCE 5fTMS ACI 530/ASCE 5ITMS 402-95 doesFrame Seams reinforcement ratio shall be less than General 402-95 in its entirety. not contain provisions for wall frame

0.15fmlfy was added. The maximum beams. Thus, NEHRP is morespacing of transverse reinforcement was restrictive and the sections are notincreased from 1/4 of the beam depth to equivalent.1/2 of the beam depth.

8.12.6 Wall The limit of factored axial compression 2115.2 SSC uses ACI 530/ASCE 5fTMS ACI 530/ASCE 5ITMS 402-95 doesFrame force was changed from 0.30Anfm to General 402-95 in its entirety. not contain provisions for wall frameColumns 0.15Anfm. The limit ofminimum column columns. Thus, NEHRP is more

dimension was decreased from 32 restrictive and the sections are notinches to 24 inches. equivalent.

8.12.7 Wall The definition of the dimension ofthe 2115.2 SSC uses ACI 530/ASCE 5fTMS ACI 530/ASCE 5ITMS 402-95 doesFrame Seam- beam-column intersection was changed General 402-95 in its entirety. not contain provisions for wall frameColumn from a multiple of the bar diameters to beam-column intersections; Thus,Intersection Eq. 8.12.7.1-1 and Eq. 8.12.7.1-2. A NEHRP is more restrictive and the

restriction that the shear stress shall not sections are not equivalent.exceed 7 roots fm was added.


Chanaed Provisions in SBC and NEHRP JudC_ESS_S.&S,SLLC_C.

1994NEHRP

9.9.1.2 ShearPanelsSheathed withOther SheetMaterials

9.9.1.2 ShearPanelsSheathed withOther SheetMaterials

Changes

Previously, light framed walls sheathedwith lath and plaster. gypsum sheathingboards, gypsum wallboard, or fiberboardsheets could be used to resistearthquake forces. Except inconventional construction, newprovisions do not allow sheet materialsother than structural-use materials to bepart of the seismic force resisting system.

Previously, light framed walls sheathedwith lath and plaster, gypsum sheathingboards. gypsum wallboard, or fiberboardsheets could be used to resistearthquake forces. Except inconventional construction, newprovisions do not allow sheet materialsother than structural-use materials to bepart of the seismic force resisting system.


1997 SSC

2308.2.4FiberboardSheathing

Table2308.2.4AllowableWorkingStress Shears

Table 2306.1FasteningSchedule

2501.0GypsumBoard andPlaster

2308.2.3

AltemateBraced

Wall Panels

Changes

The section and tables nowdifferentiate between regularfiberboard and structural fiberboard.

SBC allows the use of gypsumboard and plaster to resist seismicforces in wood-framed buildings.

This section was added to allowaltemate braced wall panels forcertain conditions.

Comments

Since NEHRP does not allow the useof fiberboard sheets except inconventional construction. it is morestringent than SBC. Thus, the twosection are judged not equivalent.

Since the 1994 NEHRP does notallow the use of gypsum board andsimilar materials to resist seismicforces at all, it is more stringent.Thus. the sections are not equivalentfor wood-framed buildings.

The SBC section is a relaxation ofthe wall bracing requirements forcertain conditions. Since NEHRPhas no altemate provisions. it is morestringent. Thus. the sections arejudged not equivalent.


Table 3B: Changed Provisions in SBC and NEHRP Judged EquivalentCHAPTER 1: GENERAL PROVISIONS


1.6.2.2.1 The requirement for periodic special 1708.4 No changes Since SBC already has theSpecial inspection during and upon completion of Reinforced modifications NEHRP has made, theInspection for reinforcing steel placement in Concrete sections are judged equivalent.Reinforcing intennediate concrete moment framesSteel and concrete shear walls was added.

The requirement for periodic specialinspection ofthe placement of steel inreinforced masonry shear walls andordinary moment frames was deleted.

1.6.2.2.2 The requirement for continuous special 1708.4 No changes SBC requires inspection of welding ofSpecial inspection during the welding of Reinforced all reinforcing in accordance withInspection for reinforcing steel was defined to pertain to Concrete ASTM A706. Thus, SBC is moreReinforcing steel resisting flexural and axial forces in stringent and the sections are judgedSteel intennediate and special moment frames equivalent.

of concrete, and in boundary members ofconcrete shear walls.

1.6.2.3 The requirement for special inspection 1708.4 No changes By not making the modificationsSpecial during and on completion ofthe Reinforced NEHRP incolllorated, SBC is nowInspection of placement of concrete for intennediate Concrete actually more stringent. Thus, theConcrete and special moment frames and sections are judged equivalent.

boundary members of concrete shearwalls was added. The requirement forperiodic special inspection duringplacement of concrete in reinforcedconcrete frames and shear walls wasdeleted.

1.6.2.6.2 Bolts in connections Identified as not 1708.3 High- No changes SBC requires that all high-strengthSpecial being slip-critical or SUbject to direct Strength Bolts bolts require inspection inInspection of tension need not be inspected for bolt accordance with AISC. Thus, SSC isStructural tension other than to ensure that the more stringent and the sections areSteel Bolts plies of the connected elements have judged equivalent.



Table 3B: Ch dP SBC d NEHRP Judaed E t1994NEHRP Changes 1997SBC Changes Comments

1.6.2.7.1 The requirement for continuous special 1708.6 Wood No changes Since sse has the modification thatSpecial inspection during field gluing operations Construction NEHRP has made, the sections areInspection of was defined to be for elements of the judged equivalent.Structural seismic force resisting system.Wood

1.6.2.7.2 The requirement for periodic special 1708.6 Wood No changes Since sse has the modification thatSpecial inspection for nailing, bolting, anchoring, Construction NEHRP has made, the sections areInspection of and other fastening was defined to jUdged equivalent.Structural pertain to all seismic components.Wood

1.6.3.1 The requirement for a sample at 1706 Test No changes sse does not specify testingTesting of fabricator's plant and the testing of Procedure methods directly. Rather, theyReinforcing reinforcing steel used in certain accept any nationally recognizedSteel applications was deleted. organization in the business of

establishing test procedures ascriteria for testing of materials. Thus,by rationale, SSC and NEHRP arejudged equivalent.

1.6.3.1.1 The requirement to examine the certified 1706 Test No changes sse does not specify testingTesting of mill test reports for each shipment of Procedure methods directly. Rather, theyReinforcing reinforcing steel was defined to pertain to accept any nationally recognizedSteel steel used to resist flexural and axial organization in the business of

forces in reinforced concrete establishing test procedures asintermediate and special moment frames criteria for testing of materials. Thus,and boundary members of reinforced by rationale, sse and NEHRP areconcrete or reinforced masonry shear judged equivalent.walls.

SBC

.....

-125 - NIST Code Comparison

1994 NEHRP



Table 3B: Changed Provisions in SBC and NEHRP Judged EquivalentChanges I 1997 SBC I Changes I Comments

Where ASTM A615 reinforcing steel is 1706 Test No changes SSC does not specify testingused to resist earthquake-induced Procedure methods directly. Rather, theyflexural and axial forces in special accept any nationally recognizedmoment frames and in wall boundary organization in the business ofelements of shear walls in bUildings of establishing test procedures asseismic performance category D and E, criteria for testing of matenals. Thus,verify that the requirements of Sec. by rationale, SSC and NEHRP are21.2.5.1 of Ref. 6-1 have been satisfied. judged equivalent.

Where ASTM A615 reinforcing steel is to 1706 Test No changes SSC does not specify testingbe welded, verify that chemical tests Procedure methods directly. Rather, theyhave been performed to determine accept any nationally recognizedweldability in accordance with Sec. 3.5.2 organization in the business ofof Ref. 6-1. establishing test procedures as

criteria for testing of materials. Thus,by rationale, SSC and NEHRP arejudged equivalent.

1.6.3.4.3Testing ofStructuralSteel

ASTM A435 and ASTM A898 are added 11706 Testcriteria on which to judge the Procedureacceptability of base metal thicker than1.5 in. that is subject to through-thickness weld shrinkage strains.

No equivalent section I 1709Inspection ofSpray-AppliedFire ResistantMaterials

No changes

Cohesion/adhesion test andacceptance criteria were added tothis section.

SSC does not specify testingmethods directly. Rather, they acceptany nationally recognizedorganization in the business ofestablishing test procedures ascriteria for testing of materials. Thus,by rationale, SSC and NEHRP arejudged equivalent.

Since NEHRP has no provisions,SSC is more stringent. Thus, thesections are judged equivalent.


ed provi:~?S~4~)C~_~d~i d~:l~c~C;t!~rCt.~~a:~J:quivalent

1994 NEHRP



Changes

New building frame systems, particularlyrelating to composite systems, wereadded. R and Cd values for ordinarymoment frames of reinforced concreteand intermediate moment frames ofreinforced concrete were increased.


1997 SBC


1607.4.1Seismic BaseShear

No changes

No changes

Changes Comments

SBe does not have any provisionsrelated to the design of compositesystems. In addition, although SBedoes not prohibit composite design,there are no provisions to design acomposite structure by rationalanalysis. Thus, the sections are notequivalent when dealing withcomposite structures. In otherstructures, however, SBe has an Rvalue equal to or less than NEHRP'svalues. Thus, the sections areequivalent.

Since SBe did not adopt the changeto NEHRP, it is more restrictive thanNEHRP. Thus, the sections areequivalent.

Appendix toehapter2PassiveEnergyDissipationSystems

This section introduces new techniquesfor incorporating energy dissipationdevices into earthquake resistantbuildings. This section is included as anappendix because it is intended to beintroduction.

No equivalent section Although SBe does not have anequivalent section, the appendix inNEHRP is just an introduction to thesystems. Therefore, the sections maybe considered equivalent.



4.5.2 Individual spread footings are required to 1804.5 No changes By not changing this provision, theFoundation have ties only for soft soil, whereas Footing 1997 SBe is more restrictive than theTies previously ties were required for Seismic Ties 1994 NEHRP. Thus, the sections

conditions when the soil is anything other are equivalent.than rock.


1994 NEHRPTable 3B: Changed Provisions in SBC and NEHRP Judged Equivalent

Changes I 1997 SBC I Changes I Comments

No equivalent section I 1804.6 This section on Foundation Walls Since the 1994 NEHRP has noFoundation was rewritten, incorporating ACI provisions regarding foundationWalls 530/ASCE 5ITMS 402-95 and ACI walls, the 1997 SBC is more

318-95. Minimum thickness tables restrictive. Thus, the sections arewere added for walls that do not equivalent.need to be designed by ACI530/SCE 5ITMS 402-95 or ACI318-95.

No equivalent section 1804.2.1 PlainConcrete,Masonry, orTimberFootings

This section now provides methodsfor detennining undisturbed orcompact soils, which was aprevious requirement.

Since the 1994 NEHRP has noprovisions regarding soil testprocedures, the 1997 SSC is morerestrictive. Thus, the sections areequivalent.


1994NEHRP Changes 1997 SBC Changes Comments

5.1 Reference Seismic Provisions for Structural steel 3502 One of the eight references in Since both codes reference the sameDocuments BUildings by AISC was added as a Referenced NEHRP were not included in SSC essential standards, the sections are

reference, and as a result, the length of Standards having to do with steel joists. judged equivalent.this chapter was reduced. Part I isbased on AISC LRFD and Part II isbased on AISC ASD. Updated versionsof LRFD by AISC and StandardSpecification, Load Tables and weightTables for Steel Joists and Joist Girdersare referenced. Another new referenceis Load and Resistance Factor DesignSpecification for Cold-formed stainlessSteel Structural Members.

5.1 Reference NEHRP uses the AISI reference for Steel 12206 ASCE took the AISI reference on Since both codes use the sameDocuments Cables (1973 Edition). Structural Steel Cables and adopted it. This document and SSC uses the more

Steel Cables section now refers to ASCE 19-95 current edition, the sections arerather than AISI. judged equivalent.


1994 NEHRP

5.2 StructuralSteel SeismicRequirements

Table 3B: Changed Provisions in SBC and NEHRP Judged EguivalentChanges I 1997 SSC I Changes I Comments

The design of structural steel members 12203.1 INo changes 1Since SBC already uses ASD andand connections to resist seismic forces General LRFD, the sections are equivalent.shall be in accordance with ASD andLRFD.

5.2.1Requirementsfor SpecialConcentricallyBracedFrames

5.3 ColdFonned SteelSeismicRequirements


This section includes the modifications tothe requirements of Seismic Provisionsfor structural Steel Buildings.

This section references SeismicProvisions for Structural Steel BUildings(1992), Specification forthe Design ofCold-Fonned steel structural Members(1986), and Load and Resistance FactorDesign Specification for Cold-Fonnedsteel Structural Members (1991).Modifications to the references areinduded. The most notable modificationis the use of an earthquake load factor of1.0 instead of 1.5.

Specification for the Design of ColdFonned Steel Structural Members, Loadand Resistance Factor DesignSpecification for Cold-Fonned SteelStructural Members and Specification forthe Design of Cold-Fonned StainlessSteel Structural Members arereferenced.

2203.2StructuralSteel SeismicRequirements

2204 ColdFonned SteelConstruction

2213 LateralResistanceFor Steel StudWall Systems

There are no modifications to thestandard adopted.

No changes

This section adds requirements forCold-Fonned Steel Stud-WallSystems.

Since SBC does not have additionalrequirements for specialconcentrically braced frames,NEHRP is more stringent. Thus, thesections are equivalent except in thecase of special concentrically bracedframes.

SBC already has the changesNEHRP has made. Thus, thesections are judged eqUivalent.

Since SBC has additionalrequirements than the tworeferences, it is more stringent thanNEHRP. Thus, the sections arejudged equivalent.


ed Provisions in SSC and NEHRP Judi.c_csM LCCU_d&S&_CS_dELCSCi_d&_43SS.


6.1 Reference The revised version ofAC1318-89 is 3502 SBC adopted AC1318-95 for Since SBC is using the later versionDocuments used as a reference. the revised Referenced reinforced and plain concrete. of ACI318, it is more upto date than

version includes Building Code Standards NEHRP. Thus, the sections areRequirements for Structural Plain equivalent.Concrete.

6.1.1.4 I Requirements for precast elements that 1912.1.1 No changes SBC already has this modification,are part of the lateral-foree-resisting Modifications but expands it to systems notsystem were added. to AC1318-95 satisfying the requirements of the

chapter, making it more stlingent.Thus, the sections are equivalent.

6.1.1.13 I Provisions for coupling beams were 11912.1.1 No changes Since SBC already has thisadded. Modifications modification, the sections are

to AC1318-95 equivalent.

6.2.4 Strength The formula to calculate the tensile 1914.1.4 No changes Since SBC already has thisBased on strength govemed by concrete failure Strength in modification, the sections areCalculations was revised. Two formulas which Tension eqUivalent.

depend on the spacing of the anchorsare given.

6.5.1 Ordinary New requirements for ordinary moment 1912.1.3.1 No changes Since SBC already had thisMoment frames with seismic performance Ordinary provision, the sections areFrames category B were added. Moment equivalent.

Frames inSeismicPerformanceCategoryB

6.6.3 Plain INew requirements for plain concrete 1912.2.3 New requirements for plain Since both codes make the sameConcrete footings, walls in the basement, Seismic concrete footings, walls in the changes, the two sections are judged

foundation, or other walls below the base Performance basement, foundation, or other eqUivalent.with seismic performance category C Category C walls below the base with seismicwere added. performance category C were

added.I


td NEHRP Judaed ESBCdPTable 3B: Ch ....1994 NEHRP Changes 1997 SBC Changes Comments

6.7.4 Plain A new provision states that structural 1912.2.4 No changes Since SSC already had thisConcrete members of plain concrete are not Seismic provision, the sections are

permitted in buildings assigned to Performance equivalent.category D or E (with some exceptions). Category D

andE

Appendix to A new appendix was added to introduce No equivalent section Although SSC does not haveChp.6 provisions for structural systems equivalent provisions, the appendix inReinforced composed of precast concrete elements NEHRP is just an introduction to theConcrete interconnected with dry connections. systems. Therefore, the sectionsStructural may be considered eqUivalent.SystemsComposedfrom Inter-connectedPrecastElements

No equivalent section 1903.2 This section adds ASTM C 595 and Since the 1994 NEHRP has noCements ASTM C 845 as cement standards. provisions, the 1997 SSC is more


No equivalent section 1903.5.2 Steel This section now requires welding Since the 1994 NEHRP has noReinforce- of reinfordng to conform to provisions, the 1997 SSC is morement ANSI/AWS D1.4. restrictive. Thus, the sections are

equivalent.

No equivalent section 1903.6 This section now requires Since the 1994 NEHRP has noAdmixtures admixtures to conform to ACI 318- provisions, the 1997 SSC is more

95 restrictive. Thus, the sections areequivalent.

No equivalent section Table 1904F This table replaces sections for Since the 1994 NEHRP has noRequirements limitations on use of certain provisions, the 1997 SSC is moreFor Concrete cementitious materials. The limits restrictive. Thus, the sections areExposed To are the same as in the previous equivalent.Deidng edition.Chemicals


1994 NEHRP

Table 3B: Changed Provisions in SBC and NEHRP Judged EquivalentChanges I 1997 SBC I Changes I Comments

No equivalent section I 1905.4 This section now allows concrete Since the 1994 NEHRP has noProportioning proportions to be based on other provisions, the 1997 SSC is moreWrthout Field experience or information, rather restrictive. Thus, the sections areExperience or than Table 1905.4 (deleted). equivalent.Trial Mixtures



1907.2Removal ofForms,Shores, andReshoring

1915Shotcrete

This section was reordered.Schedules, submittals, andunshored construction were addedto the section.

This section was added to providerequirements for shotcrete.

Since the 1994 NEHRP has noprovisions, the 1997 SSC is morerestrictive. Thus, the sections areequivalent.

Since the 1994 NEHRP has noprovisions, the 1997 SSC is morerestrictive. Thus, the sections areequivalent.


1994NEHRP

7.5.1CompositeSlabs

Changes


1997SBC

2211CompositeSlabs

Changes

This section now references ASCE3 for the design of composite slabs.

Comments

Since both codes use the samereference, these sections are judgedequivalent.


1994NEHRP


Changes

The screen wall requirements wereremoved. Requirements for wallsseparated from the basic structuralsystem were added. The restriction onuse of structural clay nonload-bearingwall tile (ASTM C56) was removed.

1997SBC

2115.6SeismicPerformanceCategoryC

No changes

Changes Comments

Since SSC did not remove therequirements that NEHRP did, it ismore stringent. Thus, the sectionsare judged equivalent.


td NEHRP Judaed ESBCdPTable 3B: Ch .... .1994 NEHRP Changes 1997 SBC Changes Comments

8.3.9 Seismic The requirement for solid grouting of 2115.8 No changes Since SSC did not remove thePerformance structural masonry that is not part of the Seismic requirements that NEHRP did, it isCategory E seismic resisting system was removed. Performance more stringent. Thus, the sections

8A.8.1 Category E are judged equivalent.

ConstructionRequirements

8.3.10 The table which contained values of the 2115.2 SSC uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 usesProperties of modulus of elasticity (8.3.10.2) was General 402-95 in its entirety. the table previously used in NEHRP.Materials removed in lieu of calculating the The table results in lower moduli in

modulus using Eq. 8.3.10.2. Thevalues clay masonry and concrete masonryof modulus of rupture in Table 8.3.10.5.1 with a strength greater than 3000 psi.were revised. Since a lower modulus results in a

lower stiffness, SSC is more stringentexcept for concrete masonry with lowstrengths. Thus, the sections areequivalent.

8.3.12 Plate, The calculations for the design axial and 2115.2 SSC uses ACI 530/ASCE 5ITMS A comparison of the equationsHeaded and shear strengths were revised (Eq. General 402-95 in its entirety. indicates that ACI 530/ASCE 5ITMSBent Bar 8.3.12.1-1,8.3.12.1-2,8.3.12.2-1, 402-95 is more stringent in two of theAnchor Bolts 8.3.12.2-2). four equations. Thus, neither section

is more stringent, the sections maybe considered equivalent.

8.6.3 Design The allowable flexural compressive 2115.2 SBC uses ACI 530/ASCE 5ITMS ACI 530/ASCE 5ITMS 402-95 usesof Plain stress for unreinforced masonry in non- General 402-95 in its entirety. the previous limit of 0.33fm. Thus,Unreinforced seismic applications is now proportional SBC is more restrictive and theMasonry to the strain up to 0.85fm. The previous sections are equivalent.Members version limited this condition to 0.33fm.


1994NEHRP

8.7.2 ShearStrength

Table 3B: Changed Provisions in SBC and NEHRP Judged EquivalentChanges I 1997 SSC I Changes I Comments

The 2/3 factor that was applied to shear 2115.2 SBC uses ACI 530/ASCE 5rrMS ACI 530/ASCE 5ITMS 402-95 usesstrength when comparing it to the shear General 402-95 in its entirety. working stress equations todemand was removed. detennine shear and, thus, a direct

comparison. However, since theintent of strength design is not toprovide a more stringent method butto provide a more accurate method ofdesign, the sections may beconsidered equivalent.



No equivalent sections

2101.3.2Support onWood

2103.1EngineeredMasonryDesign

2113 MasonryChimneys

2114 MasonryFireplacesandBarbecues

This section added an exception tothe restriction of masonry beingsupported by wood members.

This section added exceptions tothe use ofACI530/ASCE 5/TME402 for engineered masonrydesign.

These sections added requirementsfor the construction of masonrychimneys, fireplaces, andbarbecues.

Since the 1994 NEHRP has noprovisions, the 1997 SBC is morerestrictive. Thus, the sections areequivalent.

Since NEHRP only has seismicprovisions, which SBC also covers in2115, SBC is more stringent withthese extra provisions. Thus, thesections are judged equivalent.

Since the 1994 NEHRP has noprovisions, the 1997 SBC is morerestrictive. Thus, the sections areequivalent.


1994NEHRP


SSC

Changes


1997SSC

3502ReferencedStandards

Changes

The referenced standards are moreupdated versions of the standardsused by NEHRP.

-134 -

Comments

Since SBC uses the more updatedversion of standards, it is just as ormore stringent than NEHRP. Thus,the sections are equivalent.


1994 NEHRP


Table 3B: Changed Provisions in SBC and NEHRP Judged EquivalentChanges I 1997 SSC I Changes I Comments

The factor to multiply the allowable 2312.3 No changes SSC uses allowable stress design forworking stress has been increased from Strength of wood. Using the strength increase2.0 to 2.16. The phi factors have been Members and and phi factors in NEHRP, therevised. The phi factor was reduced for Connections strength is increased more than themembers in flexure with compression. value of the load factors. Therefore,The categories of connectors have been since NEHRP capacities are higherrevised. The phi factor was reduced for relative to the demand, the sectionsshear on diaphragms and shear walls. are judged equivalent.In general, with the increase in capacityand decrease in phi factor, the resultingnominal capacity is lower.


SSC

The limits for conventional constructionfor buildings have been revised. Theheight of the bUilding is no longer acriteria. The required spacing betweenbraced walls has been increased forseismic performance categories A and S.Previously all SPC A buildings could useconventional construction, now there arelimitations. Previously the maximumnumber of stories permitted forconventional construction of SPC Cbuilding was 1 and now it is 2.Previously SPC D buildings could notutilize conventional construction inseismic hazard exposure groups II andIII, and now conventional constructionmay be used for one story buildings witha maximum distance between bracedwalls of 25ft.


-135 -

Since there are no conventionalconstruction procedures in SSC, it ismore stringent than NEHRP. Thus,the sections are judged eqUivalent.


td NEHRP Judaed ESBCdPTable 3B: Ch ·1994 NEHRP Changes 1997SBC Changes Comments

9.8.1 Framing No changes 2309.1 Ceiling This section added the requirement Since NEHRP has no specificRequirements Joist and that ceiling joists shall have a provisions for minimum bearing

Rafter minimum bearing surface of 1.5 surface, SBC is more stringent.Framing inches on the top plate at each end. Thus, the sections are judged

Requirements were added for equivalent.openings in ceiling framing.

9.9.1.1 There are no restrictions for the use of 2307.6 This section removed the use of Since there are no restrictions inStructural-Use partideboards. Subfloors partideboard as subflooring (fable NEHRP on the use of partideboards,Shear Panels 2307.6C was deleted). SBC is more stringent. Thus, the

sections are equivalent.

9.9.1.1 There are no restrictions for the use of Table Parts of this table were deleted to Since there are no restrictions inStructural-Use partideboards. 2308.1C reflect restricted use of NEHRP on the use of partideboards,Shear Panels Allowable partideboard. SBC is more stringent. Thus, the

Spans for sections are equivalent.PartideboardWallSheathing

9.9.1.1 There are no restrictions for the use of 2309.3 Roof This section removed the use of Since there are no restrictions inStructural-Use partideboards. Sheathing partideboard as roof sheathing NEHRP on the use of partideboards,Shear Panels (Table 2309.3B was deleted). SBC is more stringent. Thus, the

sections are equivalent.

9.9.1.1 There are no restrictions for the use of 2311 This section has been modified Since there are no restrictions inStructural-Use partideboards. Partideboard such that partideboard is no longer NEHRP on the use of partideboards,Shear Panels Shear Walls allowed to be used as horizontal SBC is more stringent. Thus, the

diaphragm elements, only shear sections are equivalent.walls and other vertical diaphragmelements.

No equivalent section 2308.2.2 Wall This section added requirements for Since the 1994 NEHRP has noBracing wood board as use for wall bracing. provisions for woodboard used as

wall bracing, the 1997 SBC is morerestrictive. Thus, the sections areequivalent.


td NEHRP Judaed ESBCdPTable 3B: Ch .... .1994NEHRP Changes 1997 SBC Changes Comments

No equivalent section 2308.3 This section and tables have been Since NEHRP has no specificOpenings in reorganized since the previous provisions, SBC is more stringent.Exterior Walls version. The section now simply Thus, the sections are judged

Tables refers to the Tables and the Tables equivalent.

2308.3A-C are organized to provide allowable

Header Spans header spans based on GroundSnow Load, Building Width,Support Conditions, and SupportMembers.

No eqUivalent section 2308.5, Table This section now allows interior Since NEHRP has no specific2308.5 Interior bearing partitions in one and two provisions, SBC is more stringent.Bearing family dwellings to use lower Thus, the sections are judgedPartitions requirements in Table 2308.5 rather equivalent.

than the requirements for exteriorbearing walls in 2308.3.


Table 4A: Changed Provisions in ASCE 7 and NEHRP Judged Not EquivalentCHAPTER 1: GENERAL PROVISIONS

1994NEHRP Changes ASCE 7-95 Changes Comments

1.6 Quality Quality assurance provisions now apply A.9.1.6 In addition to seismic perfonnance NEHRP requires quality assuranceAssurance to other designated seismic systems in Quality category E, quality assurance provisions for other designated

seismic perfonnance category O. Assurance provisions now apply to other seismic systems for SPC 0 and Edesignated seismic systems in SPC buildings whereas ASCE 7 requires itC and 0 buildings. The for SPC C, 0, and E buildings. In thisrequirement for quality assurance respect, ASCE 7 is more stringentfor other designated seismic and the sections are equivalent.systems in buildings with SPC C, 0, NEHRP requires quality assuranceand E is now required only for provisions for other designatedcomponents with an importance seismic systems for components offactor Ip of 1.5. any importance factor, however,

ASCE 7 requires it for componentswith 1p=1.5. In this respect, NEHRPis more stringent and the sections arenot equivalent.

1.6.2.1 The requirement for continuous special A.9.1.6.2.1 The requirement for continuous The only difference in foundationFoundation inspection for placement of concrete was Foundation special inspection for placement of special inspection relates to concreteSpecial added. The requirement for continuous Special concrete in deep foundations was placement. ASCE 7 requires specialInspection special inspection for construction of Inspection added. The requirement for inspection for the placement of

drilled piles and caissons was changed continuous special inspection for concrete in deep foundationsto periodic inspection. The requirement construction ofdrilled piles and whereas NEHRP requires it for allfor periodic inspection for placement of caissons was changed to periodic foundations. Therefore, NEHRP isreinforcing steel was added. inspection. The requirement for more stringent and the sections are

periodic inspection for placement of not equivalent.reinforcing steel was added.


5~~fU_:LrJ81~:i~?&.:L~;:~~_:I_~Wa~.!i~~r.:~f~=~ Not Equivalent

1994 NEHRP


Changes

New building frame systems, particular1yrelating to composite systems, wereadded. R and Cd values for ordinarymoment frames of reinforced concreteand intermediate moment frames ofreinforced concrete were increased.

ASCE 7-95

9.2.2.2StructuralFramingSystems

Changes

New buildings frame systemsrelated to plain concrete shear wallsand special concentrically-bracedframes of steel were added.

Comments

Because of the new compositesystems added in NEHRP, there aremore structural system categoriesthan ASCE 7. ASCE 7 does notprovide a method or a rational basisfor designing composite systems,however, it does not specificallyprohibit it either. Since NEHRPaddresses composite systems, thesections are not equivalent. Withrespect to R and Cd values, there areslight differences in the tables withneither table consistently providingmore stringent values. Therefore,with respect to R and Cd values, thedocuments are essentiallyequivalent.


1994 NEHRP


Table 4A: Changed Provisions in ASCE 7 and NEHRP Judged Not EquivalentChanges I ASCE 7·95 I Changes I Comments

Load combinations are referenced to 2 In the new document, flood loads NEHRP references the previousANSI/ASCE 7-93 which differ from the Combinations are a consideration and ponding is version ofASCE 7 for loadpreviously given combinations. In of Loads no longer included in the load combinations. In ASCE 7-95, fluid,earthquake load combinations, the dead 9.2.2.6 combinations. Previously fluid, soil, soil and self-straining forces are notload factor is slightly higher but the live Combination and self straining forces were not considered in combination withand snow load factors are typically lower. of Loads included in the basic load earthquake and wind forces, whereThe vertical earthquake loads depend on combinations but were required to previously they were. In this case,Ca where they previously depended on be considered. In the new the sections are not equivalent.Av. The new vertical loads will be less document, the loads are included in When load reductions may befor soil profile A, equivalent for soil type B the load combination that does not applied, NEHRP loads may be lessand in most cases they will be larger for include wind or earthquake loads. than ASCE 7-95 since a reductionsoil types C, 0 and E. Therefore, fluid, soil, and self- may be applied on earthquake load

straining forces would previously be combinations in ASCE 7-93 whereasconsidered in combination with it is not allowed in ASCE 7-95. In thiswind and/or earthquake loads and case, ASCE 7-95 is more stringentnow they would not. A reduction in and the sections are equivalent. Theallowable stress design combina- changes to the vertical earthquaketions is no longer allowed for loads are equivalent in thecombinations involving earthquake documents.loads. The vertical earthquakeloads depend on Ca where theypreviously depended on Av. Thenew vertical loads will be less forsoil profile A, equivalent for soil typeB and in most cases they will belarger for soil types C, 0 and E.

ASCE7 ·140· NIST Code Comparison

1994 NEHRP


Table 4A: Changed Provisions in ASCE 7 and NEHRP Judged Not EquivalentChanges I ASCE 7-95 I Changes I Comments

The category for single story buildings in 9.2.2.7 The category for single story Besides masonry buildings, thethe allowable drift limit table was deleted. Deflection and buildings in the allowable drift limit allowable drift limits are equivalent.Previously there was no limit on the Drift Limits table was deleted. Previously there NEHRP has strict drift limits thatallowable drift for single story buildings in was no limit on the allowable drift apply to masonry building whichseismic hazard exposure group I. New for single story buildings in seismic ASCE 7 does not. Drift is usuallystringent allowable drift limits have been hazard exposure group I. only a concem for frame buildings, inspecified for masonry buildings. which case the documents are not

equivalent for masonry framebuildings. Drift is a measure ofdamage and not a life safety issue.In that respect, the documents areequivalent from a perfonnancestandpoint.


1994NEHRP

3.2.2ArchitecturalComponentForces andDisplacements

3.2.4 ExteriorWall PanelConnections

Changes

This section contains the new responsecoefficients to calculate the seismic loadson architectural components.

This section contains force anddisplacement requirements for exteriorwall panel connections.

ASCE7-95

9.3.2.2ArchitecturalComponentForces andDisplacements

9.3.2.4ExteriorWallPanelConnections

Changes

This section contains the newresponse coefficients to calculatethe seismic loads on architecturalcomponents.

This section contains force anddisplacement requirements forexteriorwall panel connections.

Comments

The only difference between thesections relates to powder-actuatedfasteners. NEHRP states that theymay not be used for anchorage inseismic perfonnance categories Dand E. ASCE 7 gives a Rp value thatis half the value that is in NEHRP.Thus, NEHRP is more stringentwhen it prohibits the use of powderactuated fasteners, however, ASCE7 is more stringent in the design loadwhen NEHRP allows it. Thus, thesections are not equivalent.

The force requirements are higher inNEHRP. Thus, NEHRP is morestringent and the sections are notequivalent.


1994NEHRP



Extensive requirements for bracing 9.3.3 Extensive requirements for bracing For certain HVAC system equipmentvarious mechanical and electrical Mechanical various mechanical and electrical and electrical communicationcomponents such as piping, elevators, and Electrical components such as piping, equipment, ASCE 7 has higherand storage tanks are provided. Components elevators, and storage tanks are response factors which will result in

provided. lower loads. Thus, NEHRP is morestringent in the previously statedcases, and the sections are notequivalent.


1994NEHRP

4.4.3FoundationTies

Changes


ASCE 7-95

9.4.4.3FoundationTies

No changes

Changes Comments

The foundation tie design load isdependent on Av in ASCE 7 and onCa in NEHRP. The load will belarger in NEHRP with soft soilconditions and will be less with hardrock. Thus, with soft soil conditions,the foundation tie requirements arenot equivalent.


1994NEHRP

6.1.1.4

6.1.1.5

6.1.1.7

Changes

Requirements for precast elements thatare part of the lateral-force-resistingsystem were added.

Requirements for connections of precastconcrete elements that emulate thebehavior of monolithic reinforcedconcrete construction were added.

Requirements for strong connections ofprecast concrete frames were added.

ASCE 7-95 Changes




Comments

Since no equivalent provision existsin ASCE 7, the sections are notequivalent.

Since no equivalent provision existsin ASCE 7, the sections are notequivalent.

Since no equivalent provision existsin ASeE 7, the sections are notequivalent.


Table 4A: Ch dP ASCE7 d NEHRP Judaed Not E t1994NEHRP Changes ASCE 7-95 Changes Comments

6.1.1.8 This section includes provisions for No equivalent provision Since no equivalent provision existscalculating the probable capacities of in ASCE 7, the sections are notstructural elements in precast concrete equivalent.frames.

6.1.1.12 This section contains additional No equivalent provision Since no equivalent provision existsrequirements for concrete diaphragms. in ASCE 7, the sections are not

equivalent.

6.1.1.13 Provisions for coupling beams were No equivalent provision Since no equivalent provision existsadded. in ASCE 7, the sections are not

equivalent.

6.2.2 Strength A provision was added that states that A.9.6.2.2 No changes Since ASCE 7 does not require aof Anchors anchors shall be detailed so that the Strength of particular failure sequence, the

connection failure is initiated by the Anchors sections are not equivalent.failure ofthe anchor steel rather than bythe failure of the surrounding concrete.

6.2.3 Strength The strength reduction factor for anchors A.9.6.2.2 No changes ASCE 7 does not specify a strengthBased on shall be 0.8 when the anchor failure Strength of reduction factor for the strength ofTests governs in the majority ottests and 0.65 Anchors anchors in tests. Therefore, NEHRP

when the concrete failure controls. is more stringent and the sections arenot equivalent.



Chapter 7 This new chapter presents design and 9.7 A section is reselVed for composite Although ASCE 7 does not have anyComposite detailing requirements for composite Composite structures, though no provisions provisions relating to compositeSteel and structures that are expected to provide Structures have been added thus far. structures, it does not disallow it. TheConcrete structural toughness, ductility, strength, design of a composite structureStructure and stiffness equivalent to comparable would be up to the discretion ottheDesign concrete and steel structures. designer. However, since ASCE 7Requirements does not address composite system,

the sections are not equivalent.


1994NEHRP

7.4CompositeSystems


Requirements to design composite I INo equivalent provision ISee above for discussion onsystems (partially restrained frames, composite systems.ordinal)' moment frames, specialmoment frames, concentrically bracedframes, eccentrically braced frames,reinforced concrete walls composite withsteel elements and composite shearwalls) are in this section. The sectionoutlines the design requirements forindividual elements of the system.

7.5.1CompositeSlabs

7.5.2CompositeBeams

7.5.3 EncasedCompositeColumns


Additional requirements for specialmoment frames are given as follows. Amaximum distance from the maximumconcrete compression fiber to the plasticneutral axis is given. Compressionelements that are fully encased by areinforced concrete cover (min 2'1 do notneed to meet the width-thickness ratioprovided that concrete is confined byhoop reinforcement in regions whereplastic hinges are expected to occur.

This section references LRFD for thedesign of encased composite columns.Additional requirements for seismicperformance categol)' C, 0 and E aregiven. Most of the additionalrequirements are related to concretereinforcing.

9.5 Steel

9.6 StructuralConcrete

9.5 Steel

9.5 Steel



See steel section for any changes

See specific material sections forany changes.

Although NEHRP referencesdocuments common to ASCE 7, itprovides additional requirements.Thus, the sections are not equivalent.

The documents are equivalent incomposite beam designrequirements since they bothreference LRFD. Since NEHRP isless stringent in the width-thicknessrequirement, the documents areequivalent in this respect. SinceNEHRP has an extra requirement forthe maximum distance to the plasticneutral axis, the documents are notequivalent in this respect.

NEHRP requires additional concretedetailing that is similar torequirements in the ACI. SinceASCE 7 references LRFD and ACIthe referenced provisions are thesame but the concrete detailingwould not be used in conjunction withsteel as NEHRP requires it. Thus,the sections are not equivalent.


Table 4A: Ch dP ASCE7 d NEHRP Judaed Not E t1994 NEHRP Changes ASCE 7-95 Changes Comments

7.5.4 Filled This section outlines the requirements for 9.5 Steel See specific material sections for NEHRP has additional requirementsComposite filled composite columns. LRFD is 9.6 Structural any changes. for composite columns that usesColumns referenced and additional requirements Concrete sections from various references.

are given for seismic perfonnance Although ASCE 7 references thecategories D and E. same documents, the provisions are

not required in conjunction with eachother. Thus, the sections are notequivalent.

7.6 This section includes requirements for 9.5 Steel See specific material sections for ASCE 7 does not have a sectionComposite connections in structures with composite 9.6 Structural any changes. dedicated to composite connections.Connections or dual steel-concrete systems where Concrete Much of the requirements in NEHRP

seismic loads are transferred. reference documents that ASCE 7references. Since there areadditional requirements, the sectionsare not equivalent.

ASCE7 ·145. NIST Code Comparison

Chanaed Provisions in ASCE 7 and NEHRP Jud

1994NEHRP

8.1 General

Changes


ASCE 7-95

9.8 Masonry

Changes

This section incorporates ACI530/ASCE 5ITMS 402-95 in itsentirety. Modifications to thisreference were removed.

Comments

ACI 530/ASCE 5ITMS 402-95 didincorporate strength design for theseismic provisions. Therefore, themethodology approach is the same.However, rather than develop aseparate set of strength designprovisions, the standard takes theexisting working stress designmethodology and uses load factors,phi factors, and a 3.325 increase ofallowable working stress values. Thedetailing provisions in the standardessentially remain the same. Incomparing ACI 530 and NEHRP, theformulas to calculate strengthcapacities appear to be equivalent,although NEHRP tends to be a bitmore restrictive. In the detailingprovisions, similar checks arerequired in both documents.However, NEHRP is more restrictivewith the parameters it sets, such asmaximum size of reinforcement,bundling of reinforcing bars, andhook development lengths in tension.Based on the comparison of ACI 530and NEHRP, NEHRP appears to bemore stringent. Thus, the sectionsare not equivalent.


1994 NEHRP


8.3.8 SeismicPerfonnanceCategory D


The screen wall requirements were ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 doesremoved. Requirements for walls 5ITMS 402-95 in its entirety. not have provisions for wallsseparated from the basic structural separated from the basic structuralsystem were added. The restriction on system. Thus, NEHRP is moreuse of structural clay nonload·bearing restrictive and the sections are notwall tile (ASTM C56) was removed. equivalent.

The required roughened surface ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 doesexposure for concrete placement next to 5ITMS 402-95 in its entirety. not have provisions for roughenedmasonry that is not designed with a surface exposure for concreteseparation joint was increased from placement next to masonry. Thus,1/16" to 1/8". NEHRP is more restrictive and the

sections are not equivalent.



8.5.4DefonnationRequirements

ASCE7


The calculation of embedment length(Eq. 8.4.5.2) was modified. Arequirement for 6 inches of minimumembedment length for wire was added.The calculation of embedment length forhooks (Eq. 8.4.5.4.2) was modified. Lapsplices are no longer allowed in plastichinge zones.

This section was rewritten to beconsistent with the defonnation criteriaset forth in Chapter 2.

ASCE 7 uses ACI 530/ASCE5ITMS 402-95 in its entirety.



-147·

ACI 530/ASCE 5ITMS 402-95 allowsthe use of bundled bars. Thus,NEHRP is more restrictive and thesections are not equivalent.

Due to the equation parameters, adirect comparison was not possible.However, the equation in ACI530/ASCE 5ITMS 402-95 onlyconsiders the diameter of the bar andthe strength of steel. The equationsin NEHRP also take into accountclear cover and strength of masonry.Based on this, NEHRP may beconsidered more stringent and thesections are not equivalent.

ACI530/ASCE 5ITMS 402-95 doesnot contain defonnation provisions,only strength provisions. Thus,NEHRP is more restrictive and thesections are not equivalent.


1994NEHRP



The critical strain ratio was reduced from ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 does0.003 to 0.002. The critical strain ratio is 5ITMS 402-95 in its entirety. not define a critical strain ratio. Thus,used to calculate the maximum NEHRP is more stringent and thereinforcement ratio. sections are not equivalent.



8.11.3FlangedShear Walls

ASCE7

The equations to calculate shearstrength in both the masonry andreinforcing steel were modified (Eq.8.7.3.2-1,8.7.3.3).

The requirement for confinement waschanged from a strain limit to the plastichinge zone regions. The definition of aconfined compressive zone was added.

A requirement was added that states thatsolid units shall be laid in running bondand 50% ofthe masonry units at wallintersections shall be inter1ocked. Theeffective width of flange in compressionwas changed from 1/6 ofthe wall heightto 9 times the thickness of the web. Theeffective width of flange in tension waschanged from 1/3 ofthe wall height to3/4 ofthe wall height.




-148 -

ACI 530/ASCE 5ITMS 402-95 usesone equation for calculating the shearcapacity, independent of the steelreinforcement provided. NEHRPuses separate equations forcalculating shear capacities ofmasonry and steel. Since NEHRP isthe more accurate of the twomethods, is may be considered morestringent. Thus, the sections are notequivalent.

ACI 530/ASCE 5ITMS 402-95 doesnot contain provisions forconfinement of the compressivestress zone. Thus, NEHRP is morerestrictive and the sections are notequivalent.

ACI 530/ASCE 5ITMS 402-95 doesnot contain provisions for flangedshear walls. Thus, NEHRP is morerestrictive and the sections are notequivalent.


td NEHRP Judaed Not EASCE7dPTable 4A: Ch .... .1994 NEHRP Changes ASCE 7-95 Changes Comments

8.12 Wall The requirement of where plastic hinges ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 doesFrames shall be formed was removed. 5ITMS 402-95 in its entirety. not contain provisions for wall

frames. Thus, NEHRP is morerestrictive and the sections are notequivalent.

8.12.4 A new restriction requires that actual ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 doesReinforce- yield strength shall not exceed 1.5 times 5ITMS 402-95 in its entirety. not contain provisions for wall framement the nominal yield strength. reinforcement. Thus, NEHRP is

more restrictive and the sections arenot equivalent.

8.12.5 Wall An additional restriction that the ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 doesFrame Beams reinforcement ratio shall be less than 5ITMS 402-95 in its entirety. not contain provisions for wall frame

0.15fmlfy was added. The maximum beams. Thus, NEHRP is morespacing of transverse reinforcement was restrictive and the sections are notincreased from 1/4 of the beam depth to equivalent.1/2 of the beam depth.

8.12.6 Wall The limit of factored axial compression ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 doesFrame force was changed from 0.30Anfm to 5ITMS 402-95 in its entirety. not contain provisions for wall frameColumns 0.15Anfm. The limit of minimum column columns. Thus, NEHRP is more

dimension was decreased from 32 restrictive and the sections are notinches to 24 inches. equivalent.

8.12.7 Wall The definition of the dimension ofthe ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 doesFrame Beam- beam-column intersection was changed 5ITMS 402-95 in its entirety. not contain provisions for wall frameColumn from a multiple of the bar diameters to beam-column intersections. Thus,Intersection Eq. 8.12.7.1-1 and Eq. 8.12.7.1-2. A NEHRP is more restrictive and the

restriction that the shear stress shall not sections are not equivalent.exceed 7 roots fm was added.

ASCE 7 -149 - NIST Code Comparison

Table 48: Changed Provisions in ASCE 7 and NEHRP Judged EquivalentCHAPTER 1: GENERAL PROVISIONS


1.2 Scope This section lists structures that are 1.1 Scope No major changes to section 1.1. ASCE 7 has the additional exceptionexceptions to seismic design provisions. 9.1.2 Scope In section 9.1.2, the exceptions to for one and two family dwellings inExceptions for one and two family seismic design provisions were areas where the effective peakdwellings that were previously revised. The exception for one and velocity related acceleration Av isdependent on Av, were revised to two family dwellings in areas where less than 0.10. Dwellings with thisdepend on a new coefficient Ca. the effective peak velocity related criteria is most likely encompassed

acceleration Av is less than 0.15 by the exception when the seismic

was revised to areas where Av is coefficient Ca is less than 0.15.

less than 0.10. One and two family Thus, this extra exception does not

dwellings where the seismic have a significant implication. All

coefficient Ca is less than 0.15 is a other exceptions are equivalent.

new exception. One and two family Thus, the sections are equivalent.wood frame dwellings not includedin the above stated exceptions withnot more than two stories that areconstructed in accordance with theconventional constructionrequirements are a new exception.

1.4.2 Seismic Six new soil profile types are defined in 9.1.4.2 Six new soil profile types are The seismic coefficients areCoefficients this section where previously there were Seismic defined in this section where equivalent.

4. Seismic coefficients Ca and Cv, which Coefficients previously there were 4. Seismicdepend on soil profile and seismic zone, coefficients Ca and Cv, whichare introduced in this section. Ca and Cv depend on soil profile and seismicreplace AaS and Av in the 1991 zone, are introduced in this section.provisions. All provisions that were Ca and Cv replace AaS and Av inpreviously related to Av and Aa were 93 standards. All provisions thatrevised to reflect the new coefficients. were previously related to Av and

Aa were revised to reflect the newcoefficients.


1994 NEHRP

Table 48: Changed Provisions in ASCE 7 and NEHRP Judged EquivalentChanges I ASCE 7-95 I Changes I Comments

1.4.3 SeismicHazardExposureGroup

No changes 1.5 The category numbering has been NEHRP contains three seismicClassification revised. In the new document, hazard exposure groups, whereasof Buildings category I represents structures ASCE 7 contains four classifications.and Other with a low hazard to human life in The two highest classifications areStructures the event of failure, and category IV essentially equivalent. The only

represents essential facilities. difference is that NEHRP putsCategory III was expanded to buildings containing sufficientinclude various types of quantities of toxic or explosiveoccupancies such as schools, substances in a higher category thanhealth care facilities, and jails. ASCE 7. The lowest category in

ASCE 7 includes structures thatrepresent a low hazard to human lifein the event of failure, however thelowest category in NEHRP is allbuildings not classified in the othertwo groups. Category II in ASCE 7 isall buildings not classified in the otherthree groups. Since ASCE 7 has amost stringent system ofclassification, the sections areequivalent.

1.4.4 SeismicPerfonnanceCategory

The seismic perfonnance category forseismic hazard exposure group IIIbuildings with values of Av ranging from0.10 to 0.15g was increased from C to Dto reduce the risk of collapse in essentialservice buildings in regions of moderateseismicity.

9.1.4.4SeismicPerfonnanceCategory

The seismic perfonnance categoryfor seismic hazard exposure groupIII buildings with values of Avranging from 0.10 to 0.15g wasincreased from C to D to reduce therisk of collapse in essential servicebuildings in regions of moderateseismicity.

The seismic perfonnance categoriesare equivalent.


1994 NEHRP



The requirement for periodic special A.9.1.6.2.2.1 The requirement for periodic special IThe special inspection requirementsinspection dUring and upon completion of Special inspection during and upon for reinforcing steel are equivalent.reinforcing steel placement in Inspection for completion of reinforcing steelintennediate concrete moment frames Reinforcing placement in intennediate concreteand concrete shear walls was added. Steel moment frames and concrete shearThe requirement for periodic special walls was added. The requirementinspection ofthe placement of steel in for periodic special inspection ofthereinforced masonry shear walls and placement of steel in reinforcedordinary moment frames was deleted. masonry shear walls was deleted.


The requirement for continuous special A.9.1.6.2.2.2 The requirement for continuousinspection during the welding of Special special inspection during thereinforcing steel was defined to pertain to Inspection for welding of reinforcing steel wassteel resisting flexural and axial forces in Reinforcing defined to pertain to steel resistingintennediate and special moment frames Steel flexural and axial forces inof concrete, and in boundary members of intennediate and special momentconcrete shear walls. frames of concrete, and in

boundary members of concreteshear walls.

The special inspection requirementsfor reinforcing steel welding areequivalent.

1.6.2.3SpecialInspection ofConcrete

The requirement for special inspectionduring and on completion oftheplacement of concrete for intennediateand special moment frames andboundary members of concrete shearwalls was added. The requirement forperiodic special inspection duringplacement of concrete in reinforcedconcrete frames and shear walls wasdeleted.

A.9.1.6.2.3SpecialInspection ofConcrete

The requirement for specialinspection during and oncompletion ofthe placement ofconcrete for intennediate andspecial moment frames andboundary members of concreteshear walls was added. Therequirement for periodic specialinspection during placement ofconcrete in reinforced concreteframes and shear walls wasdeleted.

The special inspection requirementsfor concrete are equivalent.


Table 48: Ch dP ASCE7 d NEHRP Judaed E t1994 NEHRP Changes ASCE 7-95 Changes Comments

1.6.2.4 The requirement for special inspection A.9.1.6.2.4 The requirement for special The special inspection requirementsSpecial after the completion of placement of Special inspection after the completion of for prestressed concrete areInspection of prestressing steel was added. Inspection of placement of prestressing steel was equivalent.Prestressed Prestressed added.Concrete Concrete

1.6.2.6.1 An exception to continuous special A.9.1.6.2.6.1 An exception to continuous special The special inspection requirementsSpecial inspection in lieu of periodic inspection Special inspection in lieu of periodic for structural welding are equivalent.Inspection of for welds loaded to less than 50 percent Inspection of inspection for welds loaded to lessStructural oftheir design strength was added. Structural than 50 percent of their designSteel Welding Steel Welding strength was added.

1.6.2.6.2 Bolts in connections identified as not A.9.1.6.2.6.2 Bolts in connections identified as The special inspection requirementsSpecial being slip-critical or sUbject to direct Special not being slip-critical or subject to for structural steel bolts areInspection of tension need not be inspected for bolt Inspection of direct tension need not be equivalent.Structural tension other than to ensure that the Structural inspected for bolt tension other thanSteel Bolts plies of the connected elements have Steel Bolts to ensure that the plies of the

been brought into snug contact. connected elements have beenbrought into snug contact.

1.6.2.7.1 The requirement for continuous special A.9.1.6.2.7.1 The requirement for continuous The special Inspection requirementsSpecial inspection during field gluing operations Special special inspection during field gluing for structural wood are equivalent.Inspection of was defined to be for elements of the Inspection of operations was defined to be forStructural seismic force resisting system. Structural elements of the seismic forceWood Wood resisting system.

1.6.2.7.2 The requirement for periodic special A.9.1.6.2.7.2 The requirement for periodic special The special inspection requirementsSpecial inspection for nailing, bolting, anchoring, Special inspection for nailing, bolting, for structural wood are equivalent.Inspection of and other fastening was defined to Inspection of anchoring, and other fastening wasStructural pertain to all seismic components. Structural defined to pertain to all seismicWood Wood components.


1994 NEHRP



The criteria for requiring special A.9.1.6.2.8 The criteria for requiring special The special inspection requirementsinspection changed from the Special inspection changed from the for architectural components areperformance criteria factor P, which Inspection of performance criteria factor P, which equivalent.depends on seismic hazard exposure Architectural depends on seismic hazardgroup and the item to be braced, to the Components exposure group and the item to beseismic performance category, which braced, to the seismic performancedepends on Av and seismic hazard category, which depends on Avandexposure group. Exceptions to periodic seismic hazard exposure group.special inspection were added and Exceptions to periodic specialadditional items requiring inspection was inspection were added andadded. additional items requiring inspection

was added.1.6.2.9SpecialInspection ofMechanicaland ElectricalComponents

The criteria for requiring specialinspection changed from performancecriteria Pto seismic performancecategory (see above). The itemsrequiring special inspection were revised.

A.9.1.6.2.9SpecialInspection ofMechanicaland ElectricalComponents

The criteria for requiring specialinspection changed fromperformance criteria P to seismicperformance category (see above).The items requiring specialinspection were revised.

The special inspection requirementsfor mechanical and electricalcomponents are equivalent.

1.6.3.1Testing ofReinforcingSteel

The requirement for a sample atfabricator's plant and the testing ofreinforcing steel used in certainapplications was deleted.

A.9.1.6.1.1Testing ofReinfordngSteel

The requirement for a sample at IThe testing requirements forfabricator's plant and the testing of reinfordng steel are equivalent.reinforcing steel used in certainapplications was deleted.


The requirement to examine the certifiedmill test reports for each shipment ofreinforcing steel was defined to pertain tosteel used to resist flexural and axialforces in reinforced concreteintermediate and special moment framesand boundary members of reinforcedconcrete or reinforced masonry shearwalls.

A.9.1.6.3.1.1Testing ofReinforcingSteel

The requirement to examine thecertified mill test reports for eachshipment of reinfordng steel wasdefined to pertain to steel used toresist flexural and axial forces inreinforced concrete intermediateand special moment frames andboundary members of reinforcedconcrete or reinforced masonryshear walls.

The testing requirements forreinfordng steel are equivalent.


td NEHRP Judaed EASCE7dPTable 48: Ch ... ...1994 NEHRP Changes ASCE 7-95 Changes Comments

1.6.3.1.2 Where ASTM A615 reinforcing steel is A.9.1.6.3.1.2 Where ASTM A615 reinforcing The testing requirements forTesting of used to resist earthquake-induced Testing of steel is used to resist earthquake- reinforcing steel are equivalent.Reinforcing flexural and axial forces in special Reinforcing induced flexural and axial forces inSteel moment frames and in wall boundary Steel special moment frames and in wall

elements of shear walls in bUildings of boundary elements of shear walls inseismic performance category D and E, buildings of seismic performanceverify that the requirements of Sec. category D and E, verify that the21.2.5.1 of Ref. 6-1 have been satisfied. requirements of Sec. 22.2.5.1 of

Ref. 9.6-1 have been satisfied.

1.6.3.1.3 Where ASTM A615 reinforcing steel is to A.9.1.6.3.1.3 Where ASTM A615 reinforcing The testing requirements forTesting of be welded, verify that chemical tests Testing of steel is to be welded, verify that reinforcing steel are equivalent.Reinforcing have been performed to determine Reinforcing chemical tests have beenSteel weldability in accordance with Sec. 3.5.2 Steel performed to determine weldability

of Ref. 6-1. in accordance with Sec. 3.5.2 ofRef. 9.6-1.

1.6.3.4.3 ASTM A435 and ASTM A898 are added A.9.1.6.3.4.3 ASTM A435 and ASTM A898 are The testing requirements forTesting of criteria on which to judge the Testing of added criteria on which to jUdge the structural steel are equivalent.Structural acceptability of base metal thicker than Structural acceptability of base metal thickerSteel 1.5 in. that is subject to through- Steel than 1.5 in. that is subject to

thickness weld shrinkage strains. through-thickness weld shrinkagestrains.


ed Provisions in ASeE 7 and NEHRP t~1_u_~J! Equivalent


2.3.2 Seismic The statement regarding the amount of 9.2.3.2 No changes ASCE 7 states that where the flatBase Shear snow load to include in the dead load Seismic Base roof snow load exceeds 30 psf, the

weight was deleted. Shear design snow load shall be included inthe seismic weight. With approval,the amount of snow load may bereduced to no less than 20% of thedesign snow load. NEHRP does notrequire snow load to be included inthe seismic weight. Therefore, ASCE7 is more stringent and the sectionsare equivalent.

2.3.2.1 In calculating Cs, the seismic response 9.2.3.2.1 In calculating Cs, the seismic The provisions for calculating theCalculation of coefficient, Cv replaces AvS and Ca Calculation of response coefficient, Cv replaces seismic response coefficient areSeismic replaces Aa in the equations. Using Seismic AvS and Ca replaces Aa in the equivalent.Response these new coefficients, the base shear is Response equations. Using these newCoefficient lowered for structures on rock but is Coefficient coefficients, the base shear is

increased for structures on soft soils. lowered for structures on rock but isThe base shear of a structure is V=CsW. increased for structures on soft

soils. The base shear of a structureisV=CsW.

2.5 Soil- No changes to the provisions, however, 9.2.5 Soil- Previously, ASCE 7 stated that soil- The provisions for soil-structureStructure the provisions were moved from an Structure structure interaction effects may be interaction effects are equivalent.Interaction appendix to the main body of the Interaction incorporated by using a generallyEffects document. Effects accepted procedure approved by

the authority having jurisdiction. Inthe current document, provisionsare included to incorporate soil-structure interactions.


1994 NEHRP

2.6Provisions forSeismicallyIsolatedStructures


This is a new section based on the 1994 9.2.6 This is a new section that includes IThe provisions for seismicallyUSC Appendix Chapter 16, division III. Provisions for various provisions relating to isolated structures are equivalent.The provisions have been modified to Seismically seismically isolated structures.conform to the strength based design Isolatedapproach and nomenclature of the Structuresdocument.


2.7.1.2

Appendix toChapter 2PassiveEnergyDissipationSystems

ASCE7

This new section includes requirementsto design all self-supporting structures,other than buildings, bridges and dams,that are supported by the earth, thatcany gravity loads, and that may berequired to resist the effects of anearthquake.

This section contains the requirementsfor strength acceptance criteria.

This section introduces new techniquesfor incorporating energy dissipationdevices into earthquake resistantbuildings. This section is included as anappendix because it is intended to beintroduction.

9.2.7NonbuildingStructures

9.2.7.1.2

This new section includesrequirements to design all selfsupporting structures, other thanbuildings, vehicular bridges anddams, that are supported by theearth, that cany gravity loads, andthat may be required to resist theeffects of an earthquake.

This section contains therequirements for strengthacceptance criteria.


-157 -

ASCE 7 specifically excludesvehicular bridges from nonbuildingstructures, whereas NEHRPexcludes all bridges. Thus, ASCE 7is more stringent and the sections areequivalent. All other provisions in thissection are equivalent except asnoted.

When an approved national standarddefines acceptance criteria in termsof allowable stresses, ASCE 7requires a direct comparison to bemade. NEHRP allows for acomparison to be made with theloads reduced by 1.5. Thus, ASCE 7is more stringent and the sections areequivalent.

Although ASCE 7 does not have anequivalent section, the appendix inNEHRP is just an introduction to thesystems. Therefore, the sectionsmay be considered equivalent.


1994NEHRP


No equivalent provision I 5.3 Flood IThis new section includes data and NEHRP references the previousLoads requirements to design for flood version of ASCE 7, where flood loads

loads. are not a consideration. Althoughthis is the case, floor loads are notrelated to the seismic safety of abuilding. Therefore, the sections maybe judged eqUivalent.


1994NEHRP

3.1 General

3.1.3 SeismicForces

Changes

The requirements for architectural,mechanical, and electrical componentshave been revised. The exceptions tofollowing the provisions are included.

Previously, lateral force calculations forarchitectural and mechanical/electricalequipment were separated. In the newprovisions, general fonnulas for allequipment are provided. The fonnulasdepend on Ca, importance factor of theequipment, component amplification,response factors, and vertical location ofthe equipment in the building.

ASCE 7-95

9.3.1 General

9.3.1.3SeismicForces

Changes

The requirements for architectural,mechanical, and electricalcomponents have been revised.The exceptions to following theprovisions are included.

Previously, lateral force calculationsfor architectural andmechanical/electrical equipmentwere separated. In the newprovisions, general fonnulas for allequipment are provided. Thefonnulas depend on Ca, importancefactor of the equipment, componentamplification, response factors, andvertical location of the equipment inthe building.

Comments

Breakaway walls are an additionalexception in ASCE 7. Therefore,breakaway walls would not need tofollow the provisions in this sectionaccording to ASCE 7. Although thisis the case, this is not a significantseismic life safety concern.Therefore, the sections may beconsidered equivalent.

The seismic force provisions areequivalent.


Table 48: Ch dP ASCE7 d NEHRP Judaed E t1994 NEHRP Changes ASCE 7-95 Changes Comments

3.1.4 Seismic This new section introduces formulas to 9.3.1.4 This new section introduces The provisions for seismic relativeRelative calculate the relative displacement that Seismic formulas to calculate the relative displacement are equivalent.Displacement may occur between components. Relative displacement that may occur

Displace- between components.ments

3.1.5 New importance factors are introduced 9.3.1.5 New importance factors are The provisions for the componentComponent which depend on the severity of failure of Component introduced which depend on the importance factors are equivalent.Importance the component. Importance severity offailure ofthe component.Factor Factor

3.2.6 This new section outlines additional 9.3.2.6 This new section outlines additional The requirements for suspendedSuspended requirements for bracing suspended Suspended requirements for bracing ceilings are equivalent.Ceilings ceilings. Ceilings suspended ceilings.

Design and construction references and Design and construction referencesminimum clearances are among the and minimum clearances areadditional requirements. among the additional requirements.

3.2.7 Access This new section outlines additional 9.3.2.7 This new section outlines additional The requirements for access floorsFloors requirements for bracing access floors. Access Floors requirements for bracing access are equivalent.

The weight used to calculate loads and floors. The weight used to calculatethe requirements for special access loads and the requirements forfloors are included. special access floors are included.

3.2.9 Steel This new section outlines additional 9.3.2.9 Steel This new section outlines additional The requirements for steel storageStorage requirements for bracing steel storage Storage requirements for bracing steel racks are equivalent.Racks racks. The weight used to calculate loads Racks storage racks. The weight used to

and the response factor to design calculate loads and the responsestorage racks is included. factor to design storage racks is

included.


ed Provisions in ASeE 7 and NEHRP Jud

1994 NEHRP

4.5.2FoundationTies

Changes

Individual spread footings are required tohave ties only for soft soil, whereaspreviously ties were required forconditions when the soil is anything otherthan rock.

1996 BOCA

9.4.5.2FoundationTies

Changes

This new section requires individualspread footings in seismicperformance categories D and Ewith soil profile type E or F to betied.

Comments

The requirements for foundation tiesare equivalent.


1994 NEHRP Changes ASCE 7-95 Changes Comments

5.1 Reference Seismic Provisions for Structural steel 9.5.1 Updated versions of the reference The reference documents areDocuments Buildings by AISC was added as a Reference documents are incorporated. equivalent.

reference, and as a result, the length of Documentsthis chapter was reduced. Part I isbased on AISC LRFD and Part II isbased on AISC ASD. Updated versionsof LRFD by AISC and StandardSpecification, Load Tables and weightTables for steel Joists and Joist Girdersare referenced. Another new referenceis Load and Resistance Factor DesignSpecification for Cold-formed StainlessSteel Structural Members.

5.2 Structural The design of structural steel members A.9.5.2 The design of structural steel The requirements are equivalent.Steel Seismic and connections to resist seismic forces Structural members and connections to resistRequirements shall be in accordance with ASD and Steel Seismic seismic forces shall be in

LRFD. Require- accordance with ASD and LRFD.ments

5.2.1 Require- This section includes the modifications to A.9.5.2.1 This section includes the The requirements for specialmentsfor the requirements of Seismic Provisions Requirements modifications to the requirements of concentrically braced frames areSpecial for structural Steel Buildings. for Special Seismic Provisions for Structural equivalent.Concentrically Concentri- Steel Buildings.Braced cally BracedFrames Frames


1994 NEHRP

5.3 ColdFormed steelSeismicRequirements


This section references Seismic A.9.5.3 Cold- This section references Seismic IThe cold-formed steel seismicProvisions for Structural Steel Buildings Formed steel Provisions for Structural Steel requirements are equivalent.0992), Specification forthe Design of Seismic Buildings (1992), Specification forCold-Fonned steel Structural Members Requirements the Design ofCold-Fonned Steel(1986), and Load and Resistance Factor Structural Members (1986), andDesign Specification for Cold-Formed Load and Resistance Factor DesignSteel Structural Members (1991). Specification for Cold-Formed SteelModifications to the references are Structural Members (1991).included. The most notable modification Modifications to the references areis the use of an earthquake load factor of included. The most notable1.0 instead of 1.5. modification is the use of an

earthquake load factor of 1.0instead of 1.5.


Specification for the Design of ColdFonned steel structural Members, Loadand Resistance Factor DesignSpecification for Cold-Fonned SteelStructural Members and Specification forthe Design ofCold-Formed StainlessSteel Structural Members arereferenced.

A.9.5.7 LightFramed Walls

Specification for the Design of ColdFormed steel structural Members,Load and Resistance Factor DesignSpecification for Cold-Formed SteelStructural Members andSpecification for the Design of ColdFormed stainless steel StructuralMembers are referenced.

The requirements for light-framedwalls are equivalent.


1994NEHRP


6.2.4 strengthBased onCalculations

Changes

The revised version of AC1318-89 isused as a reference. The revisedversion includes Building CodeRequirements for Structural PlainConcrete.

The formula to calculate the tensilestrength governed by concrete failurewas revised. Two formulas whichdepend on the spacing of the anchorsare given.

ASCE 7-95


A.9.6.2.2Strength ofAnchors

Changes

The revised version of AC1318-89is used as a reference. The revisedversion includes Building CodeRequirements for Structural PlainConcrete.

No changes

Comments

The reference documents areequivalent.

The provisions are equivalent.


td NEHRP Judaed EASCE7dPTable 48: Ch ...1994 NEHRP Changes ASCE 7-95 Changes Comments

6.2.4.3 The interaction equations to check the A9.6.2.2 No changes The interaction equations areCombined capacity for a combination oftension and Strength of equivalent.Tension and shear were revised. The result ofthe AnchorsShear change is less stringent interaction

equations.

6.5.1 Ordinary New requirements for ordinary moment A9.6.5.1 This new section includes The ordinary moment frameMoment frames with seismic performance Ordinary requirements for ordinary moment requirements are equivalent.Frames category B were added. Moment frames with seismic performance

Frames category B.

6.5.2 Moment A new provision was added that states A9.6.5.2 A new provision was added that The requirements are equivalent.Frames that moment frames on soil profile type E Moment states that moment frames on soil

or F with seismic performance category Frames profile type E or F with seismicB shall be an intermediate moment performance category B shall be anframe. intermediate moment frame.

6.6.3 Plain New requirements for plain concrete A9.6.6.3 New requirements for plain The requirements for plain concreteConcrete footings, walls in the basement, Plain concrete footings, walls in the are equivalent.

foundation, or other walls below the base Concrete basement, foundation, or otherwith seismic performance category C walls below the base with seismicwere added. performance category C were

added.

6.7.4 Plain A new provision states that structural A9.6.7.4 A new provision states that The requirements for plain concreteConcrete members of plain concrete are not Plain structural members of plain are equivalent.

permitted in buildings assigned to Concrete concrete are not permitted incategory 0 or E (with some exceptions). buildings assigned to category 0 or

E (with some exceptions).


1994 NEHRP

Appendix toChp.6ReinforcedConcreteStructuralSystemsComposedfrom InterconnectedPrecastElements


A new appendix was added to introduce No equivalent provision Although ASCE 7 does not have anprovisions for structural systems equivalent section, the appendix incomposed of precast concrete elements NEHRP is just an introduction to theinterconnected with dry connections. systems. Therefore, the sections

may be considered equivalent.


1994NEHRP


7.5CompositeMembers

Changes

The reference documents are listed inthis section.


ASCE 7-95

9.5 Steel


9.5 Steel


Changes



Comments

The documents that NEHRP andASCE 7 reference are equivalent.

Since NEHRP and ASCE 7 have thesame references, the sections areeqUivalent.


1994NEHRP


Changes

Thirty-fIVe material standard referenceswere added.

ASCE 7-95


Changes

ASCE 7 references ACI 530/ASCE5/TME 402-95 for masonry designprovisions.

Comments

The main design provisions areeqUivalent in the documents.Although there are no materialstandards references in ASCE 7, thesections are judged equivalent sincematerial standards do not pose a lifesafety concern.


Table 48: Ch dP ASCE7 d NEHRP Judaed E t1994NEHRP Changes ASCE 7·95 Changes Comments

8.3.9 Seismic The requirement for solid grouting of ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 doesPerformance structural masonry that is not part of the 5ITMS 402-95 in its entirety. have provisions for solid grouting ofCategory E seismic resisting system was removed. structural masonry that is not part of8A.8.1 the seismic resisting system. Thus,Construction ASCE 7 is more restrictive and theRequirements sections are equivalent.

8.3.10 The table which contained values of the ASCE 7 uses ACI 530/ASCE ACI530/ASCE 5ITMS 402-95 usesProperties of modulus of elasticity (8.3.10.2) was 5ITMS 402-95 in its entirety. the table previously used in NEHRP.Materials removed in lieu of calculating the The table results in lower moduli in

modulus using Eq. 8.3.10.2. Thevalues clay masonry and concrete masont)'of modulus of rupture in Table 8.3.10.5.1 with a strength greater than 3000 psi.were revised. Since a lower modulus results in a

lower stiffness, ASCE 7 is morestringent except for concretemasonry with low strengths. Thus,the sections are equivalent.

8.3.12 Plate, The calculations for the design axial and ASCE 7 uses ACI 530/ASCE A comparison of the equationsHeaded and shear strengths were revised (Eq. 5ITMS 402-95 in its entirety. indicates that ACI 530/ASCE 5ITMSBent Bar 8.3.12.1-1,8.3.12.1-2,8.3.12.2-1, 402-95 uses the previous limit ofAnchor Bolts 8.3.12.2-2). 0.33fm. Thus, ASCE 7 is more

restrictive and the sections areequivalent.

8.6.3 Design The allowable flexural compressive ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 usesof Plain stress for unreinforced masonry in non- 5ITMS 402-95 in its entirety. the previous limit of 0.33fm. Thus,Unreinforced seismic applications is now proportional ASCE 7 is more restrictive and theMasonry to the strain up to 0.85fm. The previous sections are equivalent.Members version limited this condition to 0.33fm.

ASCE7 ·164· NIST Code Comparison

1994NEHRP

8.7.2 ShearStrength


The 2/3 factor that was applied to shear ASCE 7 uses ACI 530/ASCE ACI 530/ASCE 5ITMS 402-95 usesstrength when comparing it to the shear 5ITMS 402-95 in its entirety. working stress equations todemand was removed. determine shear and, thus, a direct

comparison is not possible.However, since the intent of strengthdesign is not to provide a morestringent method but to provide amore accurate method of design, thesections may be consideredequivalent.


1994NEHRP



Changes


The factor to multiply the allowableworking stress has been increased from2.0 to 2.16. The phi factors have beenrevised. The phi factor was reduced formembers in flexure with compression.The categories of connectors have beenrevised. The phi factor was reduced forshear on diaphragms and shear walls.In general, with the increase in capacityand decrease in phi factor, the resultingnominal capacity is lower.

ASCE 7-95


A.9.9.2.2StrengthBased Design

Changes

Several reference documents havenew editions and there are a fewchanges in the references.

The phi factors have been revised.The phi factor was reduced formembers in flexure withcompression. Phi factors forconnectors are given. The phifactor was reduced for shear ondiaphragms and shear walls.

Comments

Since the reference to 1991 NOS isconsistent in both documents, designspecifications are essentiallyequivalent. Although there are acouple of differences in the referencedocuments, the sections are judgedto be essentially equivalent.

The provisions in the documents areequivalent.


1994 NEHRP



The limits for conventional construction A.9.9.4.1 The limits for conventional IThe limitations for conventionalfor buildings have been revised. The Construction construction for buildings have been construction are equivalent.height of the building is no longer a Limitations, revised. The height of the buildingcriteria. The required spacing between Conventional is no longer a criteria. The requiredbraced walls has been increased for Construction spacing between braced walls hasseismic perfonnance categories A and B. been increased for seismicPreviously all SPC A buildings could use perfonnance categories A and B.conventional construction, now there are Previously all SPC A buildingslimitations. Previously the maximum could use conventionalnumber of stories pennitted for construction, now there areconventional construction of SPC C limitations. Previously SPC 0building was 1 and now it is 2. buildings could not utilizePreviously SPC 0 buildings could not conventional construction in seismicutilize conventional construction in hazard exposure groups II and III,seismic hazard exposure groups II and and now conventional constructionIII, and now conventional construction may be used for one story buildingsmay be used for one story buildings with with a maximum distance betweena maximum distance between braced braced walls of 25ft.walls of 25ft.

9.9.1.2 ShearPanelsSheathed withother SheetMaterials

Previously, light framed walls sheathedwith lath and plaster, gypsum sheathingboards, gypsum wallboard, or fiberboardsheets could be used to resistearthquake forces. Except inconventional construction, newprovisions do not allow sheet materialsother than structural-use materials to bepart of the seismic force resisting system.

A.9.9.9.1.2Shear PanelsSheathed withother SheetMaterials

Previously, light framed wallssheathed with lath and plaster,gypsum sheathing boards, gypsumwallboard, or fiberboard sheetscould be used to resist earthquakeforces. Except in conventionalconstruction, new provisions do notallow sheet materials other thanstructural-use materials to be part ofthe seismic force resisting system.

The provisions in the documents areequivalent.


Table SA: Changed Provisions in OTFDC and NEHRP Judged Not EquivalentCHAPTER 1: GENERAL PROVISIONS

1994 NEHRP Changes 19950TFDC Changes Comments

1.3.2 No changes 117.2 This new section states that any NEHRP states that an existingAdditions to Additions, additions, alterations, or repairs to building addition shall be designedExisting Alternations or any structure shall conform to the and constructed so that the entireBuildings Repairs present code, however, the existing building conforms to the seismic

structure is not required to conform force resistance requirements forto the requirements of the present new buildings. Since NEHRP iscode. more stringent than OTFDC, the

sections are not equivalent.

No equivalent provision 109 Modifications may be made to the Since NEHRP does not allow forModifications provisions of the code if there are modifications to be made, it is more

practical difficulties in conforming to stringent than OTFDC. Therefore,the provisions. The modification the sections are not equivalent.must be approved by the buildingofficial and must not lessen thehealth, life safety and fire safetyrequirements.



2.2.5.1.2 Although there were no changes in this 604.10 No changes The typical anchorage that OTFDCAnchorage of section, the formula to calculate the Anchorage requires appears sufficient for lowConcrete or anchorage force in section 3.1.3 was seismic zones however, high seismicMasonry revised. zone NEHRP loads will result inWalls anchorage requirements that exceed

OTFDC. Therefore, NEHRP is morestringent and the sections are notequivalent.


ed Provisions in OTFDC and NEHRP Jud

1994NEHRP

3.1 General

Changes

The requirements for architectural,mechanical, and electlical componentshave been revised. The exceptions tofollowing the provisions are included.

19950TFOC

604.2.4Parapet Walls

No changes

Changes Comments

NEHRP has stlict design loadrequirements for parapets. Withsome limitations, OTFDC allowsunreinforced masonry parapets andthere are no provisions for bracing.Therefore, NEHRP is more stlingentand the sections are not equivalentwith respect to parapets. In all otheraspect of bracing, such as chimneys,veneers, and wall panels, NEHRPrequires bracing whereas OTFOCdoes not. Therefore, with respect tobracing, the sections are notequivalent.


1994NEHRP Changes 19950TFOC Changes Comments

4.4.3 The design loads for foundation ties are No equivalent provision Since OTFOC does not requireFoundation revised because of the change in foundation ties, NEHRP is moreTies seismic coefficients. stlingent and the sections are not

equivalent.

4.5.2 Individual spread footings are required to No equivalent provision Since OTFOC does not requireFoundation have ties only for soft soil, whereas foundation ties, NEHRP is moreTies previously ties were required for stlingent and the sections are not

conditions when the soil is anything other equivalent.than rock.

OTFOC -168 - NIST Code Comparison

Table SA: Chanaed Provisions in OTFDC and NEHRP Jud~

1994NEHRP


Changes

Specification for the Design of ColdFonned steel structural Members, Loadand Resistance Factor Design Specification for Cold-Fonned Steel structuralMembers and Specification for theDesign of Cold-Fonned Stainless SteelStructural Members are referenced.

19950TFDC

603 Metal

Changes

The type of material that metalstructural elements in walls andpartitions should be made of wasdeleted. The design referenceswere deleted.

Comments

The only requirement that iscontained in OTFDC for metal wallsis that the elements should bestraight and free of any defects.Thus, NEHRP is more stringent inrequirements and the sections arenot equivalent.


Chanaed Provisions in OTFDC and NEHRP Jud!P.!I!III!!

1994NEHRP

6.7.4 PlainConcrete

Changes

A new provision states that structuralmembers of plain concrete are notpermitted in buildings assigned tocategory 0 or E (with some exceptions).

19950TFDC

404.1Concrete andMasonryFoundationWalls

Changes

AC1318.1 is referenced for theconcrete and masonry foundationwalls provisions.

Comments

The minimum thickness and maximum height of unbalanced fill areamong the requirements given formasonry and concrete walls in seismic zones 3 and 4 in OTFDC.NEHRP exempts plain concretefootings and plain concrete foundation or basement walls provided thewall is not less than 7 1/2 inches thickand retains no more than 4 feet ofunbalanced fill. in one and two familydwellings three stories or less inheight. With a 4 foot maximumheight of unbalanced fill OTFDC willallow plain concrete foundation walls.With more than 4 feet of unbalancedfill, reinforcement is required. Therefore, the sections are equivalent forseismic zones 3 and 4. One and twofamily dwellings in seismic zone 2may be assigned to seismic performance category D. In this case, forplain concrete walls, more than 4 feetof unbalanced fill may be allowed inOTFDC whereas it is 4 footmaximum in NEHRP. Therefore, thesections are not equivalent forstructures in seismic zone 2.

OTFDC ·170· NIST Code Comparison

Table SA: Chanaed Provisions in OTFDC and NEHRP JudlIIIS_4.iI_CoS

1994NEHRP


8.3.8 SeismicPerfonnanceCategory D



Changes

The screen wall requirements wereremoved. Requirements for wallsseparated from the basic structuralsystem were added. The restriction onuse of structural clay nonload-bearingwall tile (ASTM C56) was removed.

The required roughened surfaceexposure for concrete placement next tomasonry that is not designed with aseparation joint was increased from1/16" to 1/8".


The calculation of embedment length(Eq. 8.4.5.2) was modified. Arequirement for 6 inches of minimumembedment length for wire was added.The calculation of embedment length forhooks (Eq. 8.4.5.4.2) was modified. Lapsplices are no longer allowed in plastichinge zones.

19950TFDC

604.11Reinforcement

Changes



No changes

OTFDC references ACI 530/ASCE5ITMS 402-91

Comments

Since OTFDC does not haveprovisions for walls separated fromthe basic structural system, thesections are not equivalent.

Since OTFDC does not haveprovisions for roughened surfaceexposure for concrete placementnext to masonry, the sections are notequivalent.

The reinforcement section in OTFDCdoes not address bundling of bars.Therefore, NEHRP is more restrictiveand the sections are not equivalent.

Due to the equation parameters, adirect comparison was not possible.However, the equation in ACI530/ASCE 5ITMS 402-95 onlyconsiders the diameter of the bar andthe strength of steel. The equationsin NEHRP also take into accountclear cover and strength of masonry.Based on this, NEHRP may beconsidered more stringent and thesections are not equivalent.


ed Provisions in OTFDC and NEHRP JudESLCSS_S.cS.sU_'_CXS_4S'XSEI_iS_bSSSU_4S_'

1994NEHRP


Changes

The limits for conventional constructionfor buildings have been revised. Theheight ofthe building is no longer acriteria. The required spacing betweenbraced walls has been increased forseismic performance categories A and B.Previously all SPC A buildings could useconventional construction, now there arelimitations. Previously the maximumnumber of stories permitted forconventional construction of SPC Cbuilding was 1 and now it is 2.Previously SPC 0 buildings could notutilize conventional construction inseismic hazard exposure groups II andIII, and now conventional constructionmay be used for one story buildings witha maximum distance between bracedwalls of 25ft.

19950TFDC

602.9 WallBracing

Changes

An alternate to the minimum 48inch panel width was added.

Comments

NEHRP requires the use of bracingwalls at a specified spacing. OTFDCrequires let in bracing at a specifiedspacing. Therefore, NEHRP is morestringent and the sections are notequivalent. The conventionalconstruction limitations are morestringentin NEHRP. NEHRPprescribes a maximum number ofstories according to seismicperformance category in which astructure may use conventionalconstruction. OTFOC allows all oneand two family dwellings with nomore than 3 stories to follow thecode, which is similar to conventionalconstruction. NEHRP referencesOTFOC for conventional constructionprovisions, therefore, whenconventional construction ispermitted in NEHRP, the sections areequivalent. In the cases whereconventional construction is notallowed in NEHRP but is still withinthe realm of OTFOC limits, NEHRPwould require a engineered structureand the sections are not equivalent.The structures in OTFOC for whichconventional construction is notallowed in NEHRP are 3 story SPCC, 2 and 3story SPC 0 and all SPCE structures.

OTFDC -172 - NiST Code Comparison

Table 58: Changed Provisions in OTFDC and NEHRP Judged Equivalent or Not RelevantCHAPTER 1: GENERAL PROVISIONS

1994NEHRP Changes 19950TFDC Changes Comments

1.2 Scope This section lists structures that are 103 Scope No changes OTFDC only applies to detached oneexceptions to seismic design provisions. 117 Existing and two family dwellings and oneExceptions for one and two family Structures family townhouses not more thandwellings that were previously - three stories in height, and theirdependent on Av, were revised to accessory structures. Structuresdepend on a new coefficient Ca. exempt from the provisions in

NEHRP are one and two familydwellings with Ca<0.15 and one andtwo family wood dwellings not morethan 2 stories with Ca>0.15constructed in accordance with theprescribed conventional constructionrequirements. Therefore, thestructures that are relevant to thecomparison are one and two familydwellings that are not more thanthree stories in height with Ca>0.15and one and two family three storywood dwellings with Ca>0.15. Theconventional light frame constructionprovisions are also relevant to thecomparison. The equivalence ofthese sections is not an issue sincethe scope of the documents is not thesame.

1.4.4 Seismic The seismic performance category for Outside scope of OTFDC OTFDC is a prescriptive documentPerformance seismic hazard exposure group III that does not require the calculationCategory buildings with values of Av ranging from of seismic loads. Therefore, seismic

0.15 to 0.20g was increased from C to D performance categories are outsideto reduce the risk of collapse in essential the scope of OTFDC and this sectionservice buildings in regions of moderate is not relevant to the comparison.seismicity.


Table 58: Changed Provisions in OTFDC and NEHRP Judged Equivalent or Not Relevant1994 NEHRP I Changes I 1995 OTFDC I Changes I Comments

1.6 Quality IQuality assurance provisions now apply 113.1 Types No changes OTFDC specifies that inspection shallAssurance to other designated seismic systems in of Inspection be made but the specification is not

seismic performance category D. prescriptive. The quality assuranceprovisions default to the localjurisdiction. Therefore, this section isnot relevant to the comparison.



The requirement for continuous specialinspection during field gluing operationswas defined to be for elements of theseismic force resisting system.

The requirement for periodic specialinspection for nailing, bolting, anchoring,and other fastening was defined topertain to all seismic components.


113.1.3Frame andMasonryInspection

113.1.3Frame andMasonryInspection

108 AlternateMaterials andSystems

No changes

No changes

Compliance with specificperformance based provisions ofBOCA National Codes, ICBOUniform Codes or SBCCI standardCodes may be permitted as analternate.

OTFDC states what inspections arecommonly made, however, thestructural wood inspectionrequirements default to the localjurisdiction. Therefore, this section isnot relevant to the comparison.

OTFDC states what inspections arecommonly made, however, thestructural wood inspectionrequirements default to the localjUrisdiction. Therefore, this section isnot relevant to the comparison.

NEHRP does not provide alternatesto the provisions. Equivalence to aparticular code should be judged ona case by case basis.


1994NEHRP


Changes

New bUilding frame systems, particular1yrelating to composite systems, wereadded. R and Cd values for ordinarymoment frames of reinforced concreteand intermediate moment frames ofreinforced concrete were increased.

19950TFDC Changes


Comments

OTFDC is a prescriptive documentthat does not require the calculationof seismic loads. Therefore, seismicloads are outside the scope ofOTFDC and this section is notrelevant to the comparison.

OTFDC ·174· NIST Code Comparison

Table 58: Changed Provisions in OTFDC and NEHRP Judged Equivalent or Not Relevant1994 NEHRP I Changes I 1995 OTFDC I Changes

2.2.5.2.1 INo changes. I301.5 Roof IA new table that provides roof liveComponent Load load is included.Load Effects

Comments

The required live load in NEHRPdefaults to the governing buildingcode. Therefore, a direct comparisonis not possible.




Load combinations are referenced toANSI/ASCE 7-93 which differ from thepreviously given combinations. Inearthquake load combinations, the deadload factor is slightly higher but the liveand snow load factors are typically lower.The vertical earthquake loads depend onCa where they previously depended onAv. The new vertical loads will be lessfor soil profile A, equivalent for soil type Band in most cases they will be larger forsoil types C, D and E.

The category for single story buildings inthe allowable drift limit table was deleted.Previously there was no limit on theallowable drift for single story buildings inseismic hazard exposure group I. Newstringent allowable drift limits have beenspecified for masonry buildings.



301.1 Design

301.2 ClimaticandGeographicDesignCriteria

No changes

Outside scope of OTFDC


Radon resistant construction is anew consideration.

OTFDC states that buildings andstructures shall be constructed tosupport all loads. In OTFDC, loadcombinations default to the governingjurisdiction. Therefore, loadcombinations are outside the scopeof OTFDC and this section is notrelevant to the comparison.

OTFDC is a prescriptive documentthat does not require the calculationof deflection and drift. Therefore,allowable drift is outside the scope ofOTFDC and this section is notrelevant to the comparison.

OTFDC is a prescriptive documentthat does not require the calculationof seismic loads. Therefore, seismicbase shear is outside the scope ofOTFDC and this section is notrelevant to the comparison.

Radon resistant construction is not aconsideration in NEHRP. However,this is not related to the seismicsafety of a building. Therefore, thesections may be jUdged equivalent.


Table 58: Chanaed Provisions in OTFDC and NEHRP Judaed Equivalent or Not Relevant- _C_b_CL

1994 NEHRP I Changes

3.1.3 Seismic IPreviously, lateral force calculations forForces architectural and mechanical/electrical

equipment were separated. In the newprovisions, general formulas for allequipment are provided. The formulasdepend on Ca, importance factor of theequipment, component amplification,response factors, and vertical location ofthe equipment in the building.

1995 OTFDC I Changes


Comments

OTFDC is a prescriptive documentthat requires little calculation.Therefore, the calculation of seismicforces is outside the scope ofOTFDC and this section is notrelevant to the comparison.


1994NEHRP Changes 19950TFDC Changes Comments

4.1 General No changes 401.1 The wood foundation provisions Since NEHRP does not specificallyApplications only apply to buildings not more disallow certain foundations for

than two floors and a roof and as certain buildings, OTFDC is morelong as no dimension in a stringent. Thus, the sections arebasement room or crawl space equivalent.exceeds the smaller of either thebuilding width or length.

4.2.2 Soil No changes 401.4.1 In lieu of a complete geotechnical NEHRP states that the capacity ofCapacity Geotechnical evaluation, load bearing values for the soil shall be sufficient to support

Evaluation various types of soil are given. the structure, however, no capacityvalues are prescribed. Therefore, thesections may be judged essentiallyequivalent.

4.2.1 No changes 402 Materials Material requirements for The material requirements in NEHRPStructural foundation materials such as wood, default to the materials chapters.Materials fasteners and concrete are OTFDC contains requirements that

induded. are not induded in NEHRP, such asthe minimum required compressivestrength. Therefore, the sections areequivalent.


Table 58: Changed Provisions in OTFDC and NEHRP Judged Equivalent or Not Relevant1994 NEHRP I Changes I 19950TFOC I Changes

No equivalent provision I 403.1 General I The minimum sizes for concrete ormasonry footings were revised.

Comments

Both NEHRP and OTFDC referenceACI 318 for concrete and ACt 530 formasonry. Since NEHRP does nothave any additional provisionsbeyond that, the sections areequivalent.

No equivalent provision 403.2Footings forWoodFoundations

This new section containsrequirements for wood foundations,fill material, and dimensionalrequirements for wood foundations.

Since NEHRP does not have anequivalent provision, the sections areequivalent.


1994NEHRP


Changes

Seismic Provisions for structural steelBuildings by AISC was added as areference, and as a result, the length ofthis chapterwas reduced. Part I isbased on AISC LRFD and Part II isbased on AISC ASD. Updated versionsof LRFD by AISC and StandardSpecification, Load Tables and weightTables for SteelJoists and Joist Girdersare referenced. Another new referenceis Load and Resistance Factor DesignSpecification for Cold-formed StainlessSteel Structural Members.


19950TFOC

804 Metal

Changes


The type of material that metalstructural elements in roof-ceilingconstruction should be made of wasdeleted. The design referenceswere deleted.

Comments

Steel structure design is outside thescope of OTFDC. Therefore, thissection is not relevant to thecomparison.

Since NEHRP does not have anequivalent provision, the sections areequivalent.


I 1994 NEHRP I Changes 119950TFOC I Changes I Comments IOTFOC • 177 - NIST Code Comparison

Table 58: Changed Provisions in OTFDC and NEHRP Judged Equivalent or Not Relevant1994 NEHRP I Changes I 19950TFDC I Changes

6.1 Reference IThe revised version ofACI 318-89 is 404.1 For the construction of foundationDocuments used as a reference. The revised Concrete and walls, AC1318-89 and ACI318.1-89

version includes Building Code Masonry are referenced.Requirements for Structural Plain FoundationConcrete. Walls

Comments

Since the references are the same,the sections are equivalent.

6.6.3 Plain INew requirements for plain concrete 404.1Concrete footings, walls in the basement, Concrete and

foundation, or other walls below the base Masonrywith seismic performance category C Foundationwere added. Walls

AC1318.1 is referenced forconcrete and masonry foundationwalls provisions.

NEHRP also references ACI 318.1.NEHRP contains other requirements,however, one and two familydwellings three stories or less inheight are exempted. Requirementsfor the nominal thickness andmaximum depth of unbalanced fill aregiven in OTFDC that are not inNEHRP. Therefore, the sections areequivalent.

No equivalent provision 505 ConcreteFloors (onGround)

The control joint requirements weredeleted.

Since NEHRP does not haveprovisions relating to control joints,the sections are equivalent.


1994NEHRP


Changes


19950TFDC Changes


Comments

Composite steel and concretestructure design is outside the scopeof OTFDC. Therefore, this section isnot relevant to the comparison.


Chanaed Provisions in OTFDC and NEHRP Judged Equivalent or Not Relevant~ .


8.1 General The masonry structure design approach Outside scope of OTFDC OTFDC is a prescriptive documentwas changed from working stress design that requires little calculation.to limit states design. Therefore, masonry design approach

is outside the scope of OTFDC andthis section is not relevant to thecomparison.

8.1.2 Thirty-fIVe material standard references 604.1 General This new section states that The main design provisions areReference were added. masonry construction shall be in equivalent in the documents.Documents accordance with ACI 530/ASCE Although OTFDC does not reference

5ITMS 402-91 orthe provisions in all of the material standards inthe section. NEHRP, the sections are judged

equivalent since material standardsare not critical to life safety.

8.3.9 Seismic The requirement for solid grouting of 607 Grouted No changes OTFDC does not require solidPerfonnance structural masonry that is not part ofthe Masonry grouting of structural masonry.Category E seismic resisting system was removed. Therefore, the sections are

8A.8.1 equivalent.

ConstructionRequirements

8.6.3 Design The allowable flexural compressive 604.4 No changes OTFDC prescribes allowable axialof Plain stress for unreinforced masonry in non- Allowable compressive stresses but does notUnreinforced seismic applications is now proportional Stresses address flexural compressiveMasonry to the strain up to O.85fm. The previous stresses. Therefore, since this isMembers version limited this condition to O.33fm. outside the scope of OTFDC, this

section is not relevant to thecomparison.



8.11.3 A requirement was added that states that 604.8.1.1 No changes OTFDC also requires that 50% of theFlanged solid units shall be laid in running bond Bonding masonry units at wall intersections beShear Walls and 50% of the masonry units at wall Pattern interfocked. Therefore, the sections

intersections shall be interfocked. The are equivalent in this respect. Theeffective width of flange in compression effective flange width is outside thewas changed from 1/6 of the wall height scope of OTFDC since OTFDC is ato 9 times the thickness of the web. The prescriptive document that requireseffective width of flange in tension was little calculation. Therefore, thischanged from 1/3 of the wall height to aspect of the section is not relevant3/4 of the wall height. to the comparison.


1994NEHRP



Changes


The factor to multiply the allowableworking stress has been increased from2.0 to 2.16. The phi factors have beenrevised. The phi factor was reduced formembers in flexure with compression.The categories of connectors have beenrevised. The phi factor was reduced forshear on diaphragms and shear walls.In general, with the increase in capadtyand decrease in phi factor, the resultingnominal capadty is lower.

19950TFDC

4702ReferencedStandards

Changes

Some changes


Comments

Many of the reference standards arethe same. Therefore, the sectionsare equivalent.

OTFDC is a prescriptive documentthat requires little calculation.Therefore, strength of members andconnections is outside the scope ofOTFDC and this section is notrelevant to the comparison.



9.9.1.2 Shear Previously, light framed walls sheathed Chp 7 Wall No major changes OTFDC is a prescriptive documentPanels with lath and plaster, gypsum sheathing Coverings that does not require calculationsSheathed with boards, gypsum wallboard, or fiberboard relating to seismic force resistingOther Sheet sheets could be used to resist systems. OTFDC and NEHRP bothMaterials earthquake forces. Except in allow the use of various types of

conventional construction, new sheathing on light framed walls.provisions do not allow sheet materials Therefore, the sections areother than structural-use materials to be equivalent.part of the seismic force resisting system.

NEHRP references OTFDC for woodprovisions

NEHRP references OTFDC for woodprovisions.

NEHRP references OTFDC for woodprovisions.

502.3AllowableSpans

503.1 LumberSheathing

602.3 ExteriorWalls

Values in table 502.3.1 c (DesignValues for Dimensional Lumber)have been revised and the speciesof wood have also been changed.

The maximum allowable spans forlumber used as floor sheathing wasincreased. The basis for theincrease is using higher strengthlumber.

Table 602.3a (Fastener Schedulefor Structural Members) has beenrevised. In general, the revisionsrequire smaller nails. Table 602.3b(Allowable Stud Spadng for WoodStructural Panel Wall Sheathing)has been revised. The revisionrequires a doser stud spacing forsome of the thinner wall panels andwill allow for a larger stud spacingfor some of the thicker wall panels.Table 602.3c (Allowable Spans forPartideboard Wall Sheathing) hasbeen revised. The allowable spansfor 5/16, 3/8, 7/16 thickness weredeleted.

Since NEHRP references OTFDC,the sections are equivalent.




tNot Reitd NEHRP Judaed EOTFDCdPTable 58: Ch ... -


NEHRP references OTFDC for wood 602.6.2 Previously the design was Since NEHRP references OTFDC,provisions. Plywood Box referenced and now the the sections are equivalent.

Headers requirements are located in thedocument.

NEHRP references OTFDC for wood 802.4.1 This new section states that purlins Since NEHRP references OTFDC,provisions. Purlins may be installed to reduce the span the sections are equivalent.

of the rafters.

NEHRP references OTFDC for wood 802.11 Roof The wind uplift forces on roof Since NEHRP references OTFDC,provisions. Tie-Down trusses and rafters were increased. the sections are equivalent.

Previously ASCE 7 was anacceptable alternate for determiningloads, but it is no longer referenced.

NEHRP references OTFDC for wood 803.1 Lumber This new section provides the Since NEHRP references OTFDC,provisions. Sheathing minimum required thickness for the sections are equivalent.

lumber sheathing.

NEHRP references OTFDC for wood 803.3.3 Requirements for partideboard roof Since NEHRP references OTFDC,provisions. Installation sheathing subjected to wind the sections are equivalent.

pressures of 30 psf or greater aregiven.
